2012 March 14 Wednesday
Less Sleep Raises Appetite

If you aren't getting enough sleep you may be eating too much as a result.

"We tested whether lack of sleep altered the levels of the hormones leptin and ghrelin, increased the amount of food people ate, and affected energy burned through activity," said Virend Somers, M.D., Ph.D., study author and professor of medicine and cardiovascular disease at the Mayo Clinic, Rochester, Minn.. Leptin and ghrelin are associated with appetite.

The researchers studied 17 normal, healthy young men and women for eight nights, with half of the participants sleeping normally and half sleeping only two-thirds their normal time.

Participants ate as much as they wanted during the study.

Researchers found:

  • The sleep deprived group, who slept one hour and 20 minutes less than the control group each day consumed an average 549 additional calories each day.
  • The amount of energy used for activity didn't significantly change between groups, suggesting that those who slept less didn't burn additional calories.
  • Lack of sleep was associated with increased leptin levels and decreasing ghrelin — changes that were more likely a consequence, rather than a cause, of over-eating.

"Sleep deprivation is a growing problem, with 28 percent of adults now reporting that they get six or fewer hours of sleep per night," said Andrew D. Calvin, M.D., M.P.H., co-investigator, cardiology fellow and assistant professor of medicine at the Mayo Clinic.

Have you gradually put on too much weight? Do you sleep enough? Try changing your lifestyle so that you can get more sleep.

This isn't new news. Other researchers have found a relationship between less sleep, greater appetite, and more weight gain.

By Randall Parker    2012 March 14 10:28 PM   Entry Permalink | Comments (5)
2012 February 13 Monday
7 Hours Sleep Optimal For Brain At Age 16

While 10 year olds benefit from 9+ hours sleep per night a new study finds that by age 16 optimal mental function is achieved with just 7 hours sleep per night.

A new Brigham Young University study found that 16-18 year olds perform better academically when they shave about two hours off that recommendation.

“We’re not talking about sleep deprivation,” says study author Eric Eide. “The data simply says that seven hours is optimal at that age.”

As I recall, I wasn't even getting that much since I couldn't get to sleep and then had to wake up too early to go to school. Turns out, schools really should not start that early. See my post High Schools Disrupt Natural Teen Sleep Schedules. So let the kids stay up late and go to school a couple of hours later and they'll function better. The science is clear. Maybe in 20 or 30 years public policy will catch up.

By Randall Parker    2012 February 13 10:44 PM   Entry Permalink | Comments (3)
2011 November 29 Tuesday
Neurotransmitter Hypocretin Key To Wakefulness

Light gets translated into signals to your hypothalamus which makes a neurotransmitter that governs wakefulness.

Bright light arouses us. Bright light makes it easier to stay awake. Very bright light not only arouses us but is known to have antidepressant effects. Conversely, dark rooms can make us sleepy. It's the reason some people use masks to make sure light doesn't wake them while they sleep.

So I wonder: Should we use light alarm clocks rather than sound alarm clocks? Seriously, anyone reading this use a clock tied to a light source that either suddenly or gradually grows brighter to wake yourself up in the morning? Sound seems like an unnatural thing to use to wake up. Light at least is causing signals to be sent to the brain that trigger hormonal changes that ready your body to waken. So why not use light to wake up? Seems healthier.

The hypothalamus is key to waking up. It is also key to regulation of hunger, thirst, and body temperature. Hey, have your body warm up before you wake up and then wake up thirsty and feeling really ready to get going. Can light do that for us?

Now researchers at UCLA have identified the group of neurons that mediates whether light arouses us — or not. Jerome Siegel, a professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA, and colleagues report in the current online edition of the Journal of Neuroscience that the cells necessary for a light-induced arousal response are located in the hypothalamus, an area at the base of the brain responsible for, among other things, control of the autonomic nervous system, body temperature, hunger, thirst, fatigue — and sleep.

Mice without enough of the neurotransmitter hypocretin can't stay away in the light. Lack of hypocretin causes narcolepsy in humans and also people with Parkinson's don't have enough of it.

These cells release a neurotransmitter called hypocretin, Siegel said. The researchers compared mice with and without hypocretin and found that those who didn't have it were unable to stay awake in the light, while those who had it showed intense activation of these cells in the light but not while they were awake in the dark.

This same UCLA research group earlier determined that the loss of hypocretin was responsible for narcolepsy and the sleepiness associated with Parkinson's disease. But the neurotransmitter's role in normal behavior was, until now, unclear.

Suppose one has a smart phone with a speaker jack. Could the alarm on a smart phone be used to somehow trigger a light? How to make the alarm sound on a headset jack feed into triggering a light switch? Anyone know of off-the-shelf parts available do this?

By Randall Parker    2011 November 29 08:44 PM   Entry Permalink | Comments (7)
2011 November 25 Friday
REM Sleep State Takes Edge Off Painful Events

When a physician at a U.S. Department of Veterans Affairs hospital in the Seattle noticed a blood pressure drug was preventing recurring nightmares a UC Berkeley researcher got interested in why. Turns out the drug suppresses the neurotransmitter norepinephrine and that during REM sleep norepinephrine goes down so that the brain can process painful memories in order to take the edge off them the next day. So in the REM sleep state it appears the brain processes emotionally difficult experiences to enable you to better handle these memories the next day.

They say time heals all wounds, and new research from the University of California, Berkeley, indicates that time spent in dream sleep can help.

UC Berkeley researchers have found that during the dream phase of sleep, also known as REM sleep, our stress chemistry shuts down and the brain processes emotional experiences and takes the painful edge off difficult memories.

The findings offer a compelling explanation for why people with post-traumatic stress disorder (PTSD), such as war veterans, have a hard time recovering from painful experiences and suffer reoccurring nightmares.They also offer clues into why we dream.

"The dream stage of sleep, based on its unique neurochemical composition, provides us with a form of overnight therapy, a soothing balm that removes the sharp edges from the prior day's emotional experiences," said Matthew Walker, associate professor of psychology and neuroscience at UC Berkeley and senior author of the study to be published this Wednesday, Nov. 23, in the journal Current Biology.

A good night's sleep is probably of great enduring value after an emotionally painful day. Make it a point to go to sleep earlier after traumatic experiences.

Stress neurochemicals are suppressed during the REM phase while the brain processes emotionally laden memories.

"During REM sleep, memories are being reactivated, put in perspective and connected and integrated, but in a state where stress neurochemicals are beneficially suppressed," said Els van der Helm, a doctoral student in psychology at UC Berkeley and lead author of the study.

If you can avoid seeing or dealing with the same disturbing images twice while awake you'll be better able to handle the images after you have gotten some sleep.

Thirty–five healthy young adults participated in the study. They were divided into two groups, each of whose members viewed 150 emotional images, twice and 12 hours apart, while an MRI scanner measured their brain activity.

Half of the participants viewed the images in the morning and again in the evening, staying awake between the two viewings. The remaining half viewed the images in the evening and again the next morning after a full night of sleep.

Those who slept in between image viewings reported a significant decrease in their emotional reaction to the images. In addition, MRI scans showed a dramatic reduction in reactivity in the amygdala, a part of the brain that processes emotions, allowing the brain's "rational" prefrontal cortex to regain control of the participants' emotional reactions.

In addition, the researchers recorded the electrical brain activity of the participants while they slept, using electroencephalograms. They found that during REM dream sleep, certain electrical activity patterns decreased, showing that reduced levels of stress neurochemicals in the brain soothed emotional reactions to the previous day's experiences.

Sleep is therapeutic. Drugs can enhance the therapeutic effect. Good to know.

By Randall Parker    2011 November 25 06:18 PM   Entry Permalink | Comments (7)
2011 June 01 Wednesday
Less Sleep Lowers Testosterone

Guys, if you want to keep up your testosterone then get enough sleep.

Cutting back on sleep drastically reduces a healthy young man's testosterone levels, according to a study published in the June 1 issue of the Journal of the American Medical Association (JAMA).

Eve Van Cauter, PhD, professor in medicine and director of the study, found that men who slept less than five hours a night for one week in a laboratory had significantly lower levels of testosterone than when they had a full night's sleep. Low testosterone has a host of negative consequences for young men, and not just in sexual behavior and reproduction. It is critical in building strength and muscle mass, and bone density.

"Low testosterone levels are associated with reduced well being and vigor, which may also occur as a consequence of sleep loss" said Van Cauter.

Getting less than 5 hours sleep per night will lower testosterone as much as aging 10 to 15 years.

At least 15% of the adult working population in the US gets less than 5 hours of sleep a night, and suffers many adverse health effects because of it. This study found that skipping sleep reduces a young man's testosterone levels by the same amount as aging 10 to 15 years.

Once full body rejuvenation becomes possible it will create not just a more useful society but also one where, due to restored testosterone levels, men become more energetic, aggressive, and driven.

By Randall Parker    2011 June 01 10:56 PM   Entry Permalink | Comments (2)
2010 October 05 Tuesday
Rod Cells Control Circadian Clock

The rod cells in the eye (used for seeing black and white under low light conditions) are the only eye cell type involved in controlling the body's circadian rhythm.

But a Johns Hopkins biologist – working in collaboration with scientists at the University of Southern California and Cornell University -- unlocked part of that mystery recently. Their study found that rod cells – one of three kinds of exquisitely photosensitive cells found in the retina of the eye – are the only ones responsible for "setting" those clocks in low light conditions. What's more, the study found that rods – which take their name from their cylindrical shape – also contribute (along with cones and other retinal cells) to setting internal clocks in bright light conditions. The study appeared in a recent issue of Nature Neuroscience.

Aging people have worse sleep cycles and perhaps not coincidentally fewer rod cells. Probably yet another example of a vicious cycle in aging since insufficient sleep accelerates aging.

"Older adults often lose their rod cells to age, which means that their caretakers would be well advised to regularly and deliberately expose them to bright natural daylight in order to make sure that their natural, biological rhythms remain in sync so their sleep-wake cycles remain accurately set," Hattar said. "Otherwise, they could have sleep disturbances, such as intermittent waking or difficulty falling asleep, not to mention the impact on their appetite and other bodily functions."

So future eye rejuvenation therapies will not only help you see better but probably also help you sleep better as well.

By Randall Parker    2010 October 05 07:56 PM   Entry Permalink | Comments (0)
2010 August 02 Monday
One Night Of Sleep Not Enough To Make Up Deficit

10 hours of sleep isn't enough to recharge your brain after 5 days of sleep deficit.

DARIEN, Ill. – A study in the Aug. 1 issue of the journal Sleep suggests that a dose of extra sleep on the weekend may be good medicine for adults who repeatedly stay up too late or wake up too early during the workweek. However, even a night of 10 hours in bed may not be enough to cure the negative effects of chronic sleep restriction.

Results show that neurobehavioral impairments such as increased lapses of attention and delayed reaction times accumulated across a period of five days when sleep was restricted to less than four hours per night. Behavioral, subjective and physiological measures of alertness improved significantly after a night of recovery sleep, with larger doses of sleep producing greater gains. Yet some neurobehavioral deficits continued to linger after the maximum recovery dose of 10 hours in bed, during which participants slept for an average of about nine hours. The study suggests that complete recovery from sustained sleep restriction may require even more sleep during one night or multiple nights of extended sleep.

As the researchers point out, the body's circadian rhythm will probably prevent a lot of people from even getting 10 hours. So if you are counting on a single night's sleep to do a full recharge after a long hard week think again.

Brain performance decayed each day over 5 days of insufficient sleep.

Mean total sleep time dropped from 8.47 hours at baseline to 3.72 hours on the first night of sleep restriction. Relative to the control group, sleep restriction degraded all neurobehavioral functions across the five days of sleep loss. One night of recovery sleep then improved all neurobehavioral outcomes as sleep doses increased. However, lapses of attention, subjective sleepiness, reaction times and fatigue scores all remained elevated above baseline levels in the 27 participants who spent 10 hours in bed on the recovery night.

"The additional hour or two of sleep in the morning after a period of chronic partial sleep loss has genuine benefits for continued recovery of behavioral alertness," said Dinges. "The bottom line is that adequate recovery sleep duration is important for coping with the effects of chronic sleep restriction on the brain."

If you are pushing yourself to get a lot done at work and with home responsibilities your productivity could be falling enough to cancel out the additional hours worked.

If you sleep less than 6 hours per night for 2 weeks your performance will be like you didn't sleep for 2 days.

Previous research led by Dinges found that even relatively moderate sleep restriction can seriously impair waking neurobehavioral functions in healthy adults. The study published in the journal Sleep in 2003 found that chronic restriction of sleep to six hours or less per night for 14 consecutive days produced cognitive performance deficits equivalent to up to two nights of total sleep deprivation.

These researchers advise you to cut back on TV to get enough sleep. Hey, I've already done this: A couple of months ago I canceled my cable TV subscription and unplugged the TV. After a few weeks I didn't miss the TV at all. I sleep more too.

In a 2009 study in the journal Sleep, Dinges and Mathias Basner, MD, reported that people who worked eight hours or more woke up earlier in the morning than people who worked less than eight hours, but they did not go to bed earlier at night. The study also found that watching TV was the primary activity people engaged in before going to bed. The authors suggested that giving up some TV viewing in the evening is one strategy to reduce chronic sleep restriction.

Consider the long term health effects of sleep deprivation too. Sleep 5 or fewer hours per day and double your risk of cardiovascular disease.

Results show that eight percent of the study population reported sleeping five hours per day or less including naps, and multivariable logistic regression analysis revealed that their risk of any cardiovascular disease was more than two times higher than that of people who reported a daily sleep duration of seven hours (adjusted odds ratio = 2.20). Nine percent of participants reported sleeping nine hours or more per day, and they also had an elevated risk of cardiovascular disease (adjusted OR = 1.57). Results were adjusted for potential confounders such as age, sex, race, smoking, alcohol consumption, body mass index, physical activity, diabetes, hypertension and depression.

By Randall Parker    2010 August 02 08:48 PM   Entry Permalink | Comments (5)
2010 July 26 Monday
Late Sunset Delays Teen Sleep

Delayed nocturnal melatonin makes kids stay up too late and then become sleepy the next day.

Troy, NY – In the spring, later sunset and extended daylight exposure delay bedtimes in teenagers, according to researchers at Rensselaer Polytechnic Institute's Lighting Research Center (LRC).

"Biologically, this increased exposure to early evening light in the spring delays the onset of nocturnal melatonin, a hormone that indicates to the body when it's nighttime," explains Mariana Figueiro, Ph.D., associate professor. "This extended exposure adds to the difficulties teens have falling asleep at a reasonable hour."

The sleep-deprived brats become moody. How about totally covering the windows in their bedrooms to block out all light in the evening?

Over time when coupled with having to rise early for school, this delay in sleep onset may lead to teen sleep deprivation and mood changes, and increase risk of obesity and perhaps under-performance in school, according to Figueiro.

Kids are made to go to school too early. This is dumb. Too early rising even boosts teen car accidents.

Getting up late means less morning sun which just makes the problem worse.

"This is a double-barreled problem for teenagers and their parents," says Figueiro. "In addition to the exposure to more evening daylight, many teens also contend with not getting enough morning light to stimulate the body's biological system, also delaying teens' bedtimes."

Blue light at the right time in the morning (while in school) could shift teen clocks so they'd go to sleep earlier. Blocking blue light exposure delays onset of sleep. Got problems falling asleep? Adjust your light exposure. Be aware that evening exposure to computer screens might cause delay in sleep too.

We do not live in our natural environment. We need to engineer the environments that we do live in to match the designs of our bodies. We should engineer the intensity and frequency distribution of light across our days to control our biological clocks so that we get enough sleep and get up when we need to.

By Randall Parker    2010 July 26 11:00 PM   Entry Permalink | Comments (5)
2010 June 29 Tuesday
Brain Energy Molecule Surges During Sleep

The energy molecule ATP surges in rat brains during the early stages of sleep.

Washington, DC — In the initial stages of sleep, energy levels increase dramatically in brain regions found to be active during waking hours, according to new research in the June 30 issue of the Journal of Neuroscience. These results suggest that a surge of cellular energy may replenish brain processes needed to function normally while awake.

A good night's rest has clear restorative benefits, but evidence of the actual biological processes that occur during sleep has been elusive. Radhika Basheer, PhD, and Robert McCarley, MD, of Boston V.A. Healthcare System and Harvard Medical School, proposed that brain energy levels are key to nightly restoration.

As I sit here fighting off sleep in order to finish this post I'm thinking I need to get to sleep in order to process all the events of the day and clean out all the clutter of information and events of the day. Perhaps ATP gets used heavily to do that while asleep. But the real meaning of this study is not clear. Does more ATP get synthesized or does less ATP get used?

"This research provides intriguing evidence that a sleep-dependent energy surge is needed to facilitate the restorative biosynthetic processes," said Robert Greene, MD, PhD, of the University of Texas Southwestern, a sleep expert who was unaffiliated with the study. He observed that questions arise from the findings, such as the specific cause of the ATP surge. "The authors propose that the surge is related to decreases in brain cell activity during sleep, but it may be due to many other factors as well, including cellular signaling in the brain," he said.

Do you get enough sleep? If you don't you are probably missing out on the full restorative potential of sleep.

By Randall Parker    2010 June 29 11:02 PM   Entry Permalink | Comments (0)
2010 June 10 Thursday
Noise During Sleep Impairs Morning Performance

If you live near a highway, train tracks, or an airport consider moving.

WESTCHESTER, IL – Nighttime noise from nearby road traffic, passing trains and overhead planes disturbs sleep and impairs morning performance, according to a research abstract that will be presented Tuesday, June 8, 2010, in San Antonio, Texas, at SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC.

Results indicate that mean reaction time on a morning psychomotor vigilance task slowed significantly by 3.6 ms after exposure to recorded traffic noise during sleep, and the slowing of reaction times was directly and significantly related to increases in both the frequency and sound-pressure level of the nightly noise events. The sound of passing trains caused the highest awakening and arousal probabilities followed by automobile traffic and airplane noise. However, this ranking was not reflected in the measures of morning neurobehavioral performance, as each mode of noise caused a similar level of impairment. Furthermore, exposure to more than one of the three modes of traffic noise did not lead to stronger performance impairments than exposure to only one noise source.

If moving isn't practical then consider sound-deadening curtains, double pane windows, acoustic insulation, and other materials (e.g. cork) that will cut your sound exposure. You can even get paint that contains ceramic hollow microspheres to cut noise.

By Randall Parker    2010 June 10 09:48 PM   Entry Permalink | Comments (9)
2010 June 07 Monday
Sexsomnia Sleep Disorder

Trying to have sex while you are asleep is a sexual sleep disorder. Who knew?

WESTCHESTER, IL – Sexsomnia was reported by almost eight percent of patients at a sleep disorders center and was more common in men than women, according to a research abstract that will be presented Monday, June 7, 2010, in San Antonio, Texas, at SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC.

Results indicate that 7.6 percent of patients (63 of 832) at a sleep disorders center reported that they had initiated or engaged in sexual activity with a bed partner while asleep. The prevalence of reported sexsomnia was nearly three times higher in men (11 percent) than in women (four percent).

"There have been no previous studies of how frequently sexsomnia occurs," said co-investigator Sharon A. Chung, PhD, Sleep Research Laboratory staff scientist in the department of psychiatry at the University Health Network in Toronto, Canada. "While our finding of eight percent of people reporting sexsomnia seems really a high number, it should be stressed that we only studied patients referred to a sleep clinic. So, we would expect the numbers to be much lower in the general population."

Some people have this happen while sleep-walking. Got any ideas on how to deal with that one?

I'm thinking a more realistic online dating service should check for qualities that have heretofore been beyond the bounds of discussion in polite society. Guy got sexsomnia? He could get matched up with an insomniac nymphomaniac. He might not remember it the next morning. But she'll be happier.

By Randall Parker    2010 June 07 10:44 PM   Entry Permalink | Comments (9)
Brief Flashes Increase Nocturnal Alertness

Just 2 milliseconds of a light flash per minute boost alertness when you really ought to be sleeping.

Results indicate that subjective sleepiness decreased and objective nighttime alertness improved after participants received a two-millisecond pulse of bright light once per minute for 60 minutes. Flash exposure, as compared with darkness, elicited significant improvement in self-rated alertness and a significant 57-millisecond improvement in median reaction time on the auditory Psychomotor Vigilance Test, compared with no significant improvement after 60 minutes of darkness. This was accompanied by significant changes in the faster frequencies of the EEG following exposure to the flashes.

"We found it shocking that light exposure as brief as a few milliseconds could engender changes in alertness and brain wave activity," said principal investigator Jamie M. Zeitzer, PhD, assistant professor in the department of psychiatry and behavioral sciences at Stanford University in Palo Alto, Calif. "These results change the manner in which we think about the brain's capacity to respond to light."

Might be useful for night drivers.

How to rig up your own 2 millisecond flash? Anyone have a good idea of how short camera flashes can go?

By Randall Parker    2010 June 07 09:33 PM   Entry Permalink | Comments (3)
2010 February 17 Wednesday
Poor Teen Sleeping Due To Lack Of Blue Light?

Our technological civilization is depriving kids of the short wavelength light they need to produce enough melatonin.

In the study just published in Neuroendocrinology Letters, Dr. Figueiro and LRC Director Dr. Mark Rea found that eleven 8th grade students who wore special glasses to prevent short-wavelength (blue) morning light from reaching their eyes experienced a 30-minute delay in sleep onset by the end of the 5-day study.

If you want to go to bed later and wake up later then wear glasses that block the blue light frequencies in the morning.

"If you remove blue light in the morning, it delays the onset of melatonin, the hormone that indicates to the body when it's nighttime," explains Dr. Figueiro. "Our study shows melatonin onset was delayed by about 6 minutes each day the teens were restricted from blue light. Sleep onset typically occurs about 2 hours after melatonin onset."

The kids need more blue light in their classrooms in the morning to get their melatonin production and circadian cycle working correctly.

The problem is that today's middle and high schools have rigid schedules requiring teenagers to be in school very early in the morning. These students are likely to miss the morning light because they are often traveling to and arriving at school before the sun is up or as it's just rising. "This disrupts the connection between daily biological rhythms, called circadian rhythms, and the earth's natural 24-hour light/dark cycle," explains Dr. Figueiro.

In addition, the schools are not likely providing adequate electric light or daylight to stimulate this biological or circadian system, which regulates body temperature, alertness, appetite, hormones and sleep patterns. Our biological system responds to light much differently than our visual system. It is much more sensitive to blue light. Therefore, having enough light in the classroom to read and study does not guarantee that there is sufficient light to stimulate our biological system.

"According to our study, however, the situation in schools can be changed rapidly by the conscious delivery of daylight, which is saturated with short-wavelength, or blue, light," reports Dr. Figueiro.

Anyone use a sort of light alarm clock where a really bright light comes on in your bedroom to help you wake up in the morning? I've thought of trying one. Might help to get going in the morning, especially in winter.

By Randall Parker    2010 February 17 07:10 PM   Entry Permalink | Comments (16)
2009 November 01 Sunday
Sleep Deprivation Cut Mental Function

The brain downshifts to simpler ways of processing information when lacking sleep.

Westchester, Ill. —A study in the Nov.1 issue of the journal Sleep shows that sleep deprivation causes some people to shift from a more automatic, implicit process of information categorization (information-integration) to a more controlled, explicit process (rule-based). This use of rule-based strategies in a task in which information-integration strategies are optimal can lead to potentially devastating errors when quick and accurate categorization is fundamental to survival.

The experimental subjects were West Point cadets. So they were at similar ages, pretty healthy, and smarter than the average population. The decay here is an average. I would be curious to know what the outliers looked like. Likely a subset suffered more severe cognitive decay when sleep-deprived.

Results show that sleep deprivation led to an overall performance deficit on an information-integration category learning task that was held over the course of two days. Performance improved in the control group by 4.3 percent from the end of day one to the beginning of day two (accuracy increased from 74 percent to 78.3 percent); performance in the sleep-deprived group declined by 2.4 percent (accuracy decreased from 73.1 percent to 70.7 percent) from the end of day one to the beginning of day two.

According to co-principal investigators W. Todd Maddox, PhD, professor of psychology, and David M. Schnyer, PhD, associate professor of psychology at the Institute for Neuroscience at the University of Texas in Austin, fast and accurate categorization is critical in situations that could become a matter of life or death. However, categorization may become compromised in people who often experience sleep deprivation in fast-paced, high pressure roles such as doctors, firefighters, soldiers and even parents. Many tasks performed on a daily basis require information-integration processing rather than rule-based categorization. Examples include driving, making a medical diagnosis and performing air-traffic control.

It would be useful to know for each person how rapidly their brain function deteriorates with lack of sleep. Even more useful: an easily administered sleep impairment test that would let one know whether one is currently sleep impaired and if so by how much. Think of it as akin to an alcohol breath test to determine whether you are safe to drive. Some who is both sleep impaired and alcohol impaired especially ought not drive.

Here's the part I find especially interesting: Not all of the sleep-deprived subjects shifted to rules-based strategies for processing information. Would a more severe degree of sleep deprivation eventually cause everyone to shift to less effective approaches for cognitive processing?

Maddox and Schnyer were surprised to find that the source of the information-integration deficit was a subgroup of sleep-deprived individuals who shifted from information-integration strategies when rested to rule-based strategies when sleep deprived. Sleep-deprived participants who used information-integration strategies in both sessions showed no drop in performance in the second session, mirroring the behavior of control participants.

A brain scan that measures white matter distribution might provide predictive results over how each person's brain will respond to sleep deprivation.

The study cites previous research suggesting that differences in cortical white matter predict cognitive vulnerability to the effects of sleep deprivation.

What I want: a watch that would let me know with a sliding bar or color coding just how sleep-deprived I am at the moment. While I'm wishing: the watch also ought to tell me about nutrient deficiencies detected by nanosensors embedded in my body. When will we get such a capability? 2020? 2025?

By Randall Parker    2009 November 01 03:25 PM   Entry Permalink | Comments (2)
2009 June 24 Wednesday
PER3 Gene Determines Brain Response To Sleep Deficiency

Do you mentally function well when sleep-deprived? I personally make more spelling mistakes when writing blog posts after midnite. Given the right variant of the gene PER3 the human mind becomes more active in response to reduced sleeping.

New imaging research in the June 24 issue of The Journal of Neuroscience helps explain why sleep deprivation affects some people more than others. After staying awake all night, those who are genetically vulnerable to sleep loss showed reduced brain activity, while those who are genetically resilient showed expanded brain activity, the study found. The findings help explain individual differences in the ability to compensate for lack of sleep.

"The extent to which individuals are affected by sleep deprivation varies, with some crashing out and others holding up well after a night without sleep," said Michael Chee, MBBS, at the Duke–National University of Singapore Graduate Medical School, an expert on sleep deprivation who was not affiliated with the study. However, studying how the brain produces these behavioral differences is difficult: researchers usually do not know whether their study participants will be vulnerable to sleep deprivation until after a study is complete. Previous studies have shown conflicting results, perhaps because the study subjects differed widely in vulnerability to sleep deprivation.

In the current study, the researchers, led by Pierre Maquet, MD, at the University of Lìege in Belgium and Derk-Jan Dijk, PhD, at the University of Surrey in the United Kingdom, avoided this problem by selecting study participants based on their genes. Previous research showed that the PERIOD3 (PER3) gene predicts how people will respond to sleep deprivation. People carry either long or short variants of the gene. Those with the short PER3 variant are resilient to sleep loss — they perform well on cognitive tasks after sleep deprivation. However, those with the long PER3 variant are vulnerable — they show deficits in cognitive performance after sleep deprivation. Now the new study explains why.

Do the people with the short PER3 variant get any advantages over those with the long variant when they are well rested? It could be that lowered cognitive performance when tired also reduces harm to the brain when it is not well rested. Some of the genes that provide advantages in some environments also come at a cost in the same or other environments.

By Randall Parker    2009 June 24 11:19 PM   Entry Permalink | Comments (2)
2009 June 14 Sunday
Sleeping Soon After Emotionally Salient Learning Improves Memory Formation

Yet another study pointing to the importance of sleep for new memory formation.

WESTCHESTER, Ill. – According to a research abstract that will be presented on Thursday, June11, at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies, sleep selectively preservers memories that are emotionally salient and relevant to future goals when sleep follows soon after learning. Effects persist for as long as four months after the memory is created.

Results indicate that the sleeping brain seems to calculate what is most important about an experience and selects only what is adaptive for consolidation and long term storage. Across long delays of 24 hours, or even three–to-four months, sleeping soon after learning preserved the trade-off (compared to waiting an entire day before going to sleep).

According to lead author, Jessica Payne, PhD, of Harvard Medical School in Boston MA, It was surprising that in addition to seeing the enhancement of negative memories over neutral scenes, there was also selectivity within the emotional scenes themselves, with sleep only consolidating what is most relevant, adaptive and useful about the scenes. It was even more surprising that this selectivity lasted for a full day and even months later if sleep came soon after learning.

Click thru and read the details. In a nutshell: you are better off learning things between 7 and 9 PM (since that is closer to when you fall asleep) than between 9 and 11 AM.

Payne said that sleep is beneficial for memory and that we remember things best when we 'stagger' our learning episodes across time.

Another study found that if you learn one task and then take a nap before learning a second task that you'll learn faster. You are better off consolidating your learning on one subject before moving on to another subject.

Quality of sleep matters. A study on rats found that slow wave and rapid eye movement (REM) sleep are needed for memory consolidation. There's an aging angle to sleep and memory formation. Old people generally do not sleep as soundly. Well, poor sleep quality impairs memory formation in aging rats. One more reason we need rejuvenation therapies.

My advice: move your learning tasks to the end of the day. Read the technical book or do practice on some skill before bed time. If you can manage to do naps then learn and do mental exercises before napping.

By Randall Parker    2009 June 14 01:28 PM   Entry Permalink | Comments (1)
2009 June 10 Wednesday
TV Watching Cuts Into Sleep Time?

TV is bad for your health.

According to the authors of the study, Mathias Basner, MD, MS, MSc, and David F. Dinges, PhD, of the University of Pennsylvania School of Medicine in Philadelphia, they were surprised to find that watching television seemed to be the most important time cue for the beginning of the sleep period, rather than hours past sunset or other more biological factors. So, in fact, TV may make people stay up late, while alarm clocks make them get up early, potentially reducing sleep time below what is physiologically needed.

Sleeping less than 7-8 hours daily impairs alertness and is associated with increased obesity, morbidity and mortality. Despite this fact, up to 40 percent of Americans sleep for less than the recommended time per night.

"Given the relationship of short sleep duration to health risks, there is concern that many Americans are chronically under-sleeping due to lifestyle choices," said Dinges. Dr. Basner added that "According to our results, watching less television in the evening and postponing work start time in the morning appear to be the candidate behavioral changes for achieving additional sleep and reducing chronic sleep debt. While the timing of work may not be flexible, giving up some TV viewing in the evening should be possible to promote adequate sleep."

Since lack of sleep causes obesity and that leads to metabolic syndrome that television calling you from across the room is killing you. You might find it hard to resist the lure of the television. It is everywhere. Many are pulled in by the siren's song. But wait, I wrote this post to let you know there is a way to escape: you just have to move and then you will find yourself safely living in an Amish paradise.

By Randall Parker    2009 June 10 11:34 PM   Entry Permalink | Comments (4)
2009 June 09 Tuesday
GABA Neurotransmitter Shortage Causes Insomnia?

People with insomnia have a lower level of the neurotransmitter GABA.

WESTCHESTER, Ill. – A research abstract that will be presented on Tuesday, June 9, at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies, is the first demonstration of a specific neurochemical abnormality in adults with primary insomnia (PI), providing greater insight to the limited understanding of the condition's pathology.

Results indicate that gamma-aminobutyric acid (GABA), the most common inhibitory transmitter in the brain, is reduced by nearly 30 percent in individuals who suffer from primary insomnia for more than six months. These findings suggest that primary insomnia is a manifestation of a neurobiological state of hyperarousal, which is present during both waking and sleep at physiological and cognitive levels.

According to principal investigator Dr. John Winkelman of Brigham and Women's Hospital, at Harvard Medical School in Boston, Mass., the recognition that primary insomnia is associated with a specific neurochemical deficiency helps validate the often misunderstood complaint of insomnia.

Any good GABA booster drugs worth trying by insomniacs? GABA agonist drugs exist. But maybe foods that provide precursors to GABA are a safer bet. L glutamic acid is a precursor to GABA. But l-glutamic acid is pretty plentiful in a meat-rich diet. Lower GABA in the brain could be due to a regulatory mechanism keeping it lower. So higher dietary precursors might not help.

By Randall Parker    2009 June 09 09:56 PM   Entry Permalink | Comments (4)
REM Sleep Improves Creativity

Taking a nap that includes the stage of sleep with Rapid Eye Movement (REM) will improve your creativity when you wake up.

While evidence for the role of sleep in creative problem-solving has been looked at by prior research, underlying mechanisms such as different stages of sleep had not been explored.  Using a creativity task called a Remote Associates Test (RAT), study participants were shown multiple groups of three words (for example: cookie, heart, sixteen) and asked to find a fourth word that can be associated to all three words (sweet, in this instance).   Participants were tested in the morning, and again in the afternoon, after either a nap with REM sleep, one without REM or a quiet rest period.  The researchers manipulated various conditions of prior exposure to elements of the creative problem, and controlled for memory.

“Participants grouped by REM sleep, non-REM sleep and quiet rest were indistinguishable on measures of memory,” said Cai. “Although the quiet rest and non-REM sleep groups received the same prior exposure to the task, they displayed no improvement on the RAT test.  Strikingly, however, the REM sleep group improved by almost 40 percent over their morning performances.”

The authors hypothesize that the formation of associative networks from previously unassociated information in the brain, leading to creative problem-solving, is facilitated by changes to neurotransmitter systems during REM sleep

So if you get stuck on a problem take a nap. Here's the PNAS research paper.

Getting enough sleep will also improve your athletic performance.

WESTCHESTER, Ill. – Athletes who extended their nightly sleep and reduced accumulated sleep debt reported improvements in various drills conducted after every regular practice, according to a research abstract that will be presented on Monday, June 8, at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies.

Results of the study indicated that sleep extension in athletes was associated with a faster sprinting drill (approximately 19.12 seconds at baseline versus 17.56 seconds at end of sleep extension), increased hitting accuracy including valid serves (12.6 serves compared to 15.61 serves), and hitting depth drill (10.85 hits versus 15.45 hits).

According to the lead author of the study, Cheri Mah, M.S., researcher at the Stanford Sleep Disorders Clinic and Research Laboratory at Stanford University in CA., many of the athletes who participated in the study realized for the first time the importance of sleep and how it impacts their performance during competitions.

Exercise might not help you sleep better. But it isn't clear as to the direction of causality. It could be that people who are live wires during the day also have a harder time sleeping.

By Randall Parker    2009 June 09 09:35 PM   Entry Permalink | Comments (2)
Less Sleep Puts On Weight In Short Term Study

In a short term study sleep restriction put on the pounds.

WESTCHESTER, Ill. – According to a research abstract that will be presented on Monday, June 8 at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies, in the presence of free access to food, sleep restricted subjects reported decrease in appetite, food cravings and food consumption; however, they gained weight over the course of the study. Thus, the finding suggests that energy intake exceeded energy expenditure during the sleep restriction

Results indicate that people whose sleep was restricted experienced an average weight gain of 1.31 kilograms over the 11 days of the study. Of the subjects with restricted sleep who reported a change in their appetite and food consumption, more than 70 percent said that it decreased by day 5 of the study. A group of well rested control subjects did not experience the weight gain.

According to lead investigator Siobhan Banks, PhD, a research fellow at the University of South Australia and former assistant research professor at the University of Pennsylvania School of Medicine, it was surprising that participants did not crave foods rich in carbohydrates after sleep restriction, as previous research suggested they might. Results indicate that even though physiologically the desire to eat was not increased by sleep loss in participants, other factors such as the sedentary environment of the laboratory and the ability to snack for longer due to reduction in time spent asleep might have influenced the weight gain.

This result is consistent with other research which finds a link between lack of sleep and weight gain. This relationship might be due to the simple result that if you are awake more hours you have more time to think about food and eat. However, the lack of sleep could be boosting appetite by increasing levels of the hormone ghrelin while lowering the hormone leptin.

By Randall Parker    2009 June 09 04:18 AM   Entry Permalink | Comments (5)
2009 April 02 Thursday
Sleep Clears Brain For New Learning

Gotta go to sleep to clear the deck.

St. Louis, March 30, 2009 —A new theory about sleep's benefits for the brain gets a boost from fruit flies in this week's Science. Researchers at Washington University School of Medicine in St. Louis found evidence that sleep, already recognized as a promoter of long-term memories, also helps clear room in the brain for new learning.

The critical question: How many synapses, or junctures where nerve cells communicate with each other, are modified by sleep? Neurologists believe creation of new synapses is one key way the brain encodes memories and learning, but this cannot continue unabated and may be where sleep comes in.

"There are a number of reasons why the brain can't indefinitely add synapses, including the finite spatial constraints of the skull," says senior author Paul Shaw, Ph.D., assistant professor of neurobiology at Washington University School of Medicine in St. Louis. "We were able to track the creation of new synapses in fruit flies during learning experiences, and to show that sleep pushed that number back down."

This isn't the first research result I've come across that supports this idea. You sleep and lots of less important memories of the day basically get tossed out. You wake up the next day with a less cluttered mind better prepared to record a new set of events.

By Randall Parker    2009 April 02 11:59 PM   Entry Permalink | Comments (1)
2008 November 08 Saturday
Sleepy Feeling Means Parts Of Brain Already Asleep

Do you feel sleepy? Then parts of your brain have already switched into a sleeping mode.

Feeling sleepy?

That’s because parts of your brain are actually asleep, according to a new theoretical paper by sleep scientists at Washington State University.

Contrary to conventional wisdom, the researchers say, there’s no control center in your brain that dictates when it’s time for you to drift off to dreamland. Instead, sleep creeps up on you as independent groups of brain cells become fatigued and switch into a sleep state even while you are still (mostly) awake. Eventually, a threshold number of groups switch and you doze off.

So when you are fighting sleep you are really just keeping only part of your brain awake. Parts of your mind have already gone missing. You find yourself working more or less effectively without those parts? (maybe some hyperactive people work more effectively sleep-deprived? I'm just asking.)

This isn't a proven theory. But it makes a lot of sense.

Lead author James Krueger said the view of sleep as an “emergent property” explains familiar experiences that the top-down model doesn’t, such as sleepwalking, in which a person is able to navigate around objects while being unconscious, and sleep inertia, the sluggishness we feel upon waking up in the morning.

“If you explain it in terms of bits and pieces of the brain, instead of a top-down phenomenon, all of a sudden you can make sense of these things,” said Krueger. “The old paradigm doesn’t even address these things.”

Krueger teamed with fellow neurobiologists David Rector, Hans Van Dongen, Gregory Belenky, Jaak Panksepp and electrical engineer Sandip Roy on the work. Their paper, “Sleep as a fundamental property of neuronal assemblies,” will appear in the December issue of Nature Reviews/Neuroscience. It is available online at http://www.nature.com/nrn/journal/vaop/ncurrent/pdf/nrn2521.html.

If sleep were being directed by a control center, the whole brain would respond at the same time, said Krueger. Instead, it behaves like a self-directing orchestra in which most sections are more-or-less in sync, but a few race ahead or lag behind at any given time.

Click thru and read some of the evidence for why they think their theory makes sense. Interesting stuff.

By Randall Parker    2008 November 08 10:17 AM   Entry Permalink | Comments (2)
2008 October 25 Saturday
Sleep Deprivation Enhances False Memory Retrieval

In a Plos One paper some Swiss and German researchers report in a paper entitled Sleep Loss Produces False Memories that sleep deprivation at time of retrieval enhanced false memories. Don't trust your memories when you are tired. Caffeine prevents the inaccurate retrievals.

People sometimes claim with high confidence to remember events that in fact never happened, typically due to strong semantic associations with actually encoded events. Sleep is known to provide optimal neurobiological conditions for consolidation of memories for long-term storage, whereas sleep deprivation acutely impairs retrieval of stored memories. Here, focusing on the role of sleep-related memory processes, we tested whether false memories can be created (a) as enduring memory representations due to a consolidation-associated reorganization of new memory representations during post-learning sleep and/or (b) as an acute retrieval-related phenomenon induced by sleep deprivation at memory testing. According to the Deese, Roediger, McDermott (DRM) false memory paradigm, subjects learned lists of semantically associated words (e.g., “night”, “dark”, “coal”,…), lacking the strongest common associate or theme word (here: “black”). Subjects either slept or stayed awake immediately after learning, and they were either sleep deprived or not at recognition testing 9, 33, or 44 hours after learning. Sleep deprivation at retrieval, but not sleep following learning, critically enhanced false memories of theme words. This effect was abolished by caffeine administration prior to retrieval, indicating that adenosinergic mechanisms can contribute to the generation of false memories associated with sleep loss.

Researchers at the Washington University Memory Lab have shown that to optimize learning it is better to be tested on material than to study material a second time. Retrieval enhances memory consolidation. Also, there are optimal intervals for retesting. Well, my guess is that if you try to get tested when you are tired you'll not just recall less correctly then but also reduce the accuracy of future attempts to recall the same material. So sleep well before getting tested.

By Randall Parker    2008 October 25 10:11 PM   Entry Permalink | Comments (5)
2008 January 30 Wednesday
Sleep Weakens Excess Brain Connections

We need to sleep to unburden ourselves of an excessive strengthening of neural connections.

MADISON – Most people know it from experience: After so many hours of being awake, your brain feels unable to absorb any more—and several hours of sleep will refresh it.

Now new research from the University of Wisconsin School of Medicine and Public Health clarifies this phenomenon, supporting the idea that sleep plays a critical role in the brain’s ability to change in response to its environment. This ability, called plasticity, is at the heart of learning.

Reporting in the Jan. 20, 2008, online version of Nature Neuroscience, the UW-Madison scientists showed by several measures that synapses — nerve cell connections central to brain plasticity — were very strong when rodents had been awake and weak when they had been asleep.

The new findings reinforce the UW-Madison researchers’ highly-debated hypothesis about the role of sleep. They believe that people sleep so that their synapses can downsize and prepare for a new day and the next round of learning and synaptic strengthening.

The human brain expends up to 80 percent of its energy on synaptic activity, constantly adding and strengthening connections in response to all kinds of stimulation, explains study author Chiara Cirelli, associate professor of psychiatry.

The idea is that we form lots of connections and not all of them matter. Probably if we form similar connections day after day those end up not getting weakened by sleep.

By Randall Parker    2008 January 30 10:23 PM   Entry Permalink | Comments (2)
2008 January 08 Tuesday
90 Minute Naps Might Speed Memory Consolidation

How about a nap after an intense learning exercise to help form memories?

In this new research, which was conducted by researchers at the University of Haifa in cooperation with the Sleep Laboratory at the Sheba Medical Center and researchers from the Department of Psychology at the University of Montreal, it was revealed that a daytime nap changes the course of consolidation in the brain. Two groups of participants in the study practiced a repeated motor activity which consisted of bringing the thumb and a finger together at a specific sequence. The research examined the "how" aspect of memory in the participants' ability to perform the task quickly and in the correct sequence. One of the groups was allowed to nap for an hour and a half after learning the task while the other group stayed awake.

The group that slept in the afternoon showed a distinct improvement in their task performance by that evening, as opposed to the group that stayed awake, which did not exhibit any improvement. Following an entire night's sleep, both groups exhibited the same skill level. "This part of the research showed that a daytime nap speeds up performance improvement in the brain. After a night's sleep the two groups were at the same level, but the group that slept in the afternoon improved much faster than the group that stayed awake," stressed Prof. Karni.

This makes intuitive sense. We form more permanent memories while we sleep. We can get our brain to form memories by falling asleep.

Here is the cool part: If you are going to learn two tasks you might learn more efficiently if you nap after you learn the first task and before you learn the second task.

A second experiment showed that another aspect of memory consolidation is accelerated by sleep. It was previously shown that during the 6-8 hours after completing an effective practice session, the neural process of "how" memory consolidation is susceptible to interference, such that if, for example, one learns or performs a second, different task, one's brain will not be able to successfully remember the first trained task. A third group of participants in the University of Haifa study learned a different thumb-to-finger movement sequence two hours after practicing the first task. As the second task was introduced at the beginning of the 6-8 hour period during which the brain consolidates memories, the second task disturbed the memory consolidation process and this group did not show any improvement in their ability to perform the task, neither in the evening of that day nor on the following morning. However, when a fourth group of participants was allowed a 90 minute nap between learning the first set of movements and the second, they did not show much improvement in the evening, but on the following morning these participants showed a marked improvement of their performance, as if there had been no interference at all.

We need better methods of inducing sleep and in particular for inducing the sleep states where memories get processed.

By Randall Parker    2008 January 08 11:33 PM   Entry Permalink | Comments (6)
2007 October 24 Wednesday
Humans Do Not Adjust To Daylight Savings Time

If I was king one of the things I'd do is abolish Daylight Savings Time (though I'd ban car lock and car alarm horn beeping first). In my view Daylight Savings Time is a manifestation of the modern tendency of humans to try to deny their biological nature. No, we can't just en masse shift our sleep cycles without some cost to be paid. I like it when science produces evidence that confirms my intuitions. Well, here is some scientific evidence for the idea that Daylight Savings Time is a bad idea.

In a large survey, which examined the sleep patterns of 55,000 people in Central Europe, Roenneberg’s group now shows that the timing of sleep on free days follows the seasonal progression of dawn under standard time, but not under DST.

In a second study, they analyzed the timing of sleep and activity for eight weeks around each of the two DST transitions in 50 people, taking into account each individual’s natural clock preferences, or “chronotypes,” ranging from morning larks to night owls. They found that the timing of both sleep and peak activity levels readily adjust to the release from DST in autumn, but that the timing of activity does not adjust to the start of DST in spring, especially in those who like to stay up late and sleep in.

“While we generally think that the time changes enforced by the DST transitions are ‘only an hour,’ they have far more drastic effects if viewed in the context of the circadian clock’s seasonal changes,” Roenneberg said. “This seemingly small hour translates to a repeat of 10 weeks in the annual progression of the relationship between our sleep-wake cycle and dawn—four weeks in spring and six weeks in autumn. In effect, it’s as if the entire population of Germany, for example, is transported to Morocco in spring and back again in autumn.”

Indeed, “after taking the seasonal adjustment into account, our results show that the human circadian clock does not adjust to the DST transition,” Roenneberg said. “This is especially obvious in the late chronotypes in spring when one looks at their daily activity patterns. Essentially, their biological timing stays on standard, winter time, while they have to adjust their social schedules to the advanced clock time throughout the summer.”

A lot of high school kids are probably the ones most in need of escape from what some adults foolishly think is a good idea. Forcing kids to adhere to schedules that make them really sleepy in class is a big waste.

By Randall Parker    2007 October 24 10:11 PM   Entry Permalink | Comments (2)
2007 October 22 Monday
Sleep Deficiency Causes Emotional Overreaction

Skimp on the sleep and your emotional control will decay.

Without sleep, the emotional centers of the brain dramatically overreact to negative experiences, reveals a new brain imaging study in the October 23rd issue of Current Biology, a publication of Cell Press. The reason for that hyperactive emotional response in sleep-deprived people stems from a shutdown of the prefrontal lobe—a region that normally keeps emotions under control.

The new study from Harvard Medical School and the University of California, Berkeley is the first to explain, at the neural level, what seems to be a universal phenomenon: that sleep loss leads to emotionally irrational behavior, according to the researchers. The findings might also offer some insight into the clinical connection between sleep disruptions and psychiatric disorders.

Have a hard time controlling your emotions? Get enough sleep. You can't afford to cut corners on your sleep.

Maybe people become more primitive when they lack sleep.

In the new study, Walker’s team assigned 26 healthy people to either a sleep-deprivation group—in which participants were kept awake for about 35 hours—or a normal sleep group. On the following day, the study subjects’ brains were scanned by functional magnetic resonance imaging (fMRI), which measures brain activity on the basis of blood flow, while viewing 100 images. The images were at first emotionally neutral, but became increasingly aversive over time.

“We had predicted a potential increase in the emotional reaction from the brain [in people deprived of sleep], but the size of the increase truly surprised us,” Walker said of the study’s findings. “The emotional centers of the brain were over 60% more reactive under conditions of sleep deprivation than in subjects who had obtained a normal night of sleep. It is almost as though, without sleep, the brain reverts back to a more primitive pattern of activity, becoming unable to put emotional experiences into context and produce controlled, appropriate responses.

Do we have free will? At best the extent of our free will varies as a function of how much sleep we get, whether we take steroids (roid rage), and countless other influences.

By Randall Parker    2007 October 22 09:46 PM   Entry Permalink | Comments (5)
2007 August 05 Sunday
Night Shift Work Lowers Serotonin Neurotransmitter

If you are prone to depression don't work the late night shift.

WESTCHESTER, Ill. -- People who work rotating shifts have significantly lower levels of serotonin, a hormone and neurotransmitter in the central nervous system believed to play an important role in the regulation of sleep, according to a study published in the August 1st issue of the journal SLEEP.

Heard of anti-depressant drugs like Prozac, Celexa, Lexapro, Zoloft, or Paxil? They are all selective serotonin reuptake inhibitors (SSRIs). They work by preventing neurons from pulling serotonin back onto the internal side of neural cell membranes. That leaves more serotonin to bind to receptors which boosts certain types of neural signalling which somehow lifts people out of depression. But if you do something that lowers the amount of serotonin available (and working the night shift does this) then you are going to be more prone to depression.

Night shift workers are probably not asking for enough additional compensation to make it worth the effect on their bodies.

The study, authored by Carlos J. Pirola, PhD, of the Universidad de Buenos Aires, Argentina, focused on 683 men of self-reported European ancestry, in which 437 day workers were compared with 246 rotating shift workers. Day and night work periods started at 6 a.m. and 6 p.m. respectively. None of the subjects interchanged their job schedule.

The results showed that serotonin content differed greatly between day workers and rotating shift workers, with levels of serotonin significantly higher in day workers.

“These findings may be important not only to understand the mechanisms related to the circadian rhythm desynchronization imposed by the rotating shift work regime, but also to target truly effective therapeutic strategies that may ameliorate the associated comorbidities and behavioral problems in rotating shift workers,” said Pirola.

In addition to sleep problems, low levels of serotonin are also associated with other conditions such as anger, depression and anxiety.

What would be interesting follow-up experiments: Can high intensity lights, melatonin, or some other treatment or style of living allow people to work late shifts without lowered serotonin? Also, is some fraction of the populace able to do late shift work without getting lowered levels of serotonin?

By Randall Parker    2007 August 05 06:23 PM   Entry Permalink | Comments (10)
2007 May 07 Monday
Magnetic Pulse Induces Slow Wave Sleep State

A University of Wisconsin scientist has found a way to induce the slow wave sleep state of the brain.

Now, Giulio Tononi, a professor of psychiatry at the University of Wisconsin-Madison School of Medicine and Public Health, has discovered how to stimulate brain waves that characterize the deepest stage of sleep. The discovery could open a new window into the role of sleep in keeping humans healthy, happy and able to learn.

Tononi figured out how to use transcranial magnetic stimulation above a particular spot to induce the slow wave state of sleeping.

During slow wave activity, which occupies about 80 percent of sleeping hours, waves of electrical activity wash across the brain, roughly once a second, 1,000 times a night. In a paper being published this week in the Early Edition of the scientific journal PNAS, Tononi and colleagues, including Marcello Massimini, also of the UW-Madison School of Medicine and Public Health, described the use of transcranial magnetic stimulation (TMS) to initiate slow waves in sleeping volunteers. The researchers recorded brain electrical activity with an electroencephalograph (EEG).

A TMS instrument sends a harmless magnetic signal through the scalp and skull and into the brain, where it activates electrical impulses. In response to each burst of magnetism, the subjects' brains immediately produced slow waves typical of deep sleep, Tononi says. "With a single pulse, we were able to induce a wave that looks identical to the waves the brain makes normally during sleep."

The researchers have learned to locate the TMS device above a specific part of the brain, where it causes slow waves that travel throughout the brain. "We don't know why, but this is a very good place to evoke big waves that clearly travel through every part of the brain," Tononi says.

Tononi is going to use this capability to investigate his hypothesis that the slow wave state allows the brain to weaken connections that formed from events experienced during the day. He sees sleep as something that weakens many unimportant memories so that our brains do not become burdened with too many memories.

By Randall Parker    2007 May 07 11:10 PM   Entry Permalink | Comments (3)
2007 April 01 Sunday
Coffee Use Worse On Sleep For Night Shift Workers

If you use coffee to work a night shift then the coffee decreases the quality of your daytime recovery sleep.

Montreal, October 2, 2006 -- A new study at the Université de Montréal has concluded that people drinking coffee to get through a night shift or a night of studying will strongly hurt their recovery sleep the next day. The study published in the current issue of Neuropsychopharmacology was conducted by Dr. Julie Carrier from the Department of Psychology at the Université de Montréal. Dr. Carrier runs the Chronobiology Laboratory at the Hôpital du Sacré-Coeur de Montréal.

"We already knew that caffeine has important effects on nocturnal sleep. It increases the time taken to fall asleep, it increases the amount of awakenings, and it decreases the amount of deep sleep. We have shown that these effects of caffeine on sleep are way stronger when taken at night prior to a daytime recovery sleep episode than in the evening before a nocturnal sleep episode."

"Caffeine makes daytime sleep episodes too shallow to override the signal from the biological clock that tells the body it should be awake at this time of day," explains Dr. Carrier. "We often use coffee and other sources of caffeine during the nighttime to counteract sleepiness generated by sleep deprivation, jet lag, and shift-work. However, this habit may have important effects when you then try to recuperate during daytime."

Thirty-four moderate caffeine consumers participated in both caffeine (200 mg) and placebo (lactose) conditions in a double-blind crossover design. Seventeen subjects followed their habitual sleep–wake cycle and slept in the laboratory during the night (Night), while 17 subjects were sleep deprived for one night and recovery sleep started in the morning (DayRec). All subjects received a capsule of 100 mg of caffeine (or placebo) 3 hours before bedtime, and the remaining dose 1 hour before bedtime. Compared to placebo, caffeine lengthened sleep latency, increased stage 1, and reduced stage 2 and slow-wave sleep (SWS) in both groups. However, caffeine reduced sleep efficiency more strongly in the DayRec group, and decreased sleep duration and REM sleep only in that group.

People who stay up all night feel the greatest need to use coffee and other sleep-fighting stimulants. But they should most try to avoid use of coffee since they need quality deep sleep when they try to sleep during the day. Sorry about that late night workers.

Wondering whether to drink more coffee? Also see my posts Scientists Demonstrate Best Way To Use Caffeine and Coffee Drinking Slows Cognitive Decline.

By Randall Parker    2007 April 01 01:08 PM   Entry Permalink | Comments (0)
2007 March 18 Sunday
Sleep Gene Determines Performance Of Sleep Deprived

Whether you can function well lacking sleep in the middle of the night might come down to the length of your copies of the PERIOD3 gene.

People are known to differ markedly in their response to sleep deprivation, but the biological underpinnings of these differences have remained difficult to identify. Researchers have now found that a genetic difference in a so-called clock gene, PERIOD3, makes some people particularly sensitive to the effects of sleep deprivation. The findings, reported by Antoine Viola, Derk-Jan Dijk, and colleagues at the University of Surrey's Sleep Research Center, appear online this week in the journal Current Biology, published by Cell Press.

There are two variants of the PERIOD3 gene found in the human population, encoding either long or short versions of the corresponding protein. Each individual will possess two copies of the gene, either of which might be the long or short form. Previous work had indicated that the different forms of the gene appear to influence characteristic morning and evening activity levels—for example, "owl" versus "lark" tendencies.

In the new work, a multidisciplinary research team consisting of biological scientists and psychologists compared how individuals possessing only the longer gene variant and those possessing only the shorter one coped with being kept awake for two days, including the intervening night. The researchers found that although some participants struggled to stay awake, others experienced no problems with the task.

The results were most pronounced during the early hours of the morning (between 4 and 8 a.m.), during which individuals with the longer variant of the gene performed very poorly on tests for attention and working memory.

But how do the carriers of the short and long versions perform during the day when they have plenty of sleep?

Carriers of the longer version spent a larger portion of their sleep time in the deepest sleep state. My guess is that confers some sort of advantage. Any idea what that advantage might be?

An additional finding was that the effects of this gene on performance may be mediated by its effects on sleep. When the volunteers were allowed to sleep normally, those possessing only the longer form of the gene spent about 50% more of their time in slow-wave sleep, the deepest form of sleep. Slow-wave sleep is a marker of sleep need, and it is known that carrying a sleep debt makes it very difficult to stay awake and perform at night.

What I'd like to know: Do the people with the longer form of the gene form more memories when they sleep? I ask this because if there are two versions of the gene widespread then likely each version provides advantages and disadvantages. What advantage does the long version provide that compensates for its disadvantages when one stays up all night?

When offspring genetic engineering becomes possible prospective parents are going to be faced with thousands or even tens of thousands of trade-offs between different genetic variations for their offspring. Make your kid a night owl? Or make him wake up at the crack of dawn? Make your kid able to handle lots of sleep disruptions and get by on less sleep? Or perhaps make her brain age more slowly or form more memories per time asleep?

By Randall Parker    2007 March 18 10:07 PM   Entry Permalink | Comments (6)
2006 September 22 Friday
Lack Of Sleep Causes Inflammation, Immune Response

Chronic inflammation is now widely seen as a contributing factor to many diseases of old age. Any dietary or lifestyle choices that increase the amount of inflammation in your body is probably going to accelerate your aging and make you more prone to not just infections but chronic degenerative illnesses such as heart disease and arthritis. With that thought in mind consider that skimping on sleep increases the amount of inflammation in the body.

Researchers at UCLA are the first to show how sleep loss affects the immune system's inflammatory response and suggest sleep interventions as a possible way to address problems associated with inflammation and autoimmune disorders.

Reporting in the Sept. 6 edition of the peer-reviewed journal Archives of Internal Medicine, the research team finds that even modest sleep loss triggers cellular and genetic processes involved in the immune system's inflammatory response to disease and injury.

The findings increase understanding of sleep's role in altering immune cell physiology and suggest sleep interventions as a possible way to address inflammation associated with risk of cardiovascular disease, arthritis, diabetes and other autoimmune disorders.

"This study shows that even a modest loss of sleep for a single night increases inflammation, which is a key factor in the onset of cardiovascular disease and autoimmune disorders such as rheumatoid arthritis." said Dr. Michael Irwin, professor and director of the Cousins Center for Psychoneuroimmunology at the Semel Institute for Neuroscience and Human Behavior at UCLA.

About one-third of the people in the United States have trouble getting a good night's sleep. The problem is more prevalent among people with chronic inflammatory disorders, including heart disease. Epidemiology studies link poor sleep with risk of chronic disease in some people.

Inflammation, with its accompanying redness and swelling, occurs when the immune system floods a diseased or damaged portion of the body with infection-fighting white blood cells that promote healing. However, a variety of immune system disorders can cause the body to turn on itself, sometimes causing inflammation that can damage healthy organs and tissues.

The UCLA research team conducted blood and DNA analyses of 30 healthy adults drawn during the day across three baseline periods and after partial night sleep deprivation. The results show white blood cells called monocytes produce significantly greater amounts of two disease-fighting proteins after a night of sleep loss, compared with amounts found after a night of uninterrupted sleep.

So the dog who insisted I let him out at 4 AM this morning helped accelerate aging. I explained this to him and he was complelely indifferent.

If you can see small changes you can make to your life to up the amount of sleep you get to an adequate amount then make those changes. You'll be better off in the long run.

Update: Does anyone know of scientific research into factors that increase or decrease your need for sleep? For example, if you are doing a lot of mental work and learning during the day does that increase the need for sleep because the mind needs to spend more time processing to form lasting memories of what it learned that day? Or do high fat diets increase the need for sleep as compared to low fat diets? Or does a diet high in vegetables decrease the need for sleep?

By Randall Parker    2006 September 22 06:01 PM   Entry Permalink | Comments (12)
2006 July 23 Sunday
Sleeping With Women Drains Male Brains?

University of Vienna Austria researcher Gerhard Kloesch arranged for childless couples to sleep 10 days together and 10 days apart. Both wives and husbands slept more poorly together and men suffered more degraded performance than the wives did.

While men thought they slept better with a partner, and women believed they didn't, actually both sexes had more disturbed sleep, even when they did not have sex. Lack of sleep led to increased stress hormone levels in men, and reduced their ability to perform simple cognitive tests the next day.

Women can handle interruptions more easily. The reason is probably Darwinian: Natural selection selected for females that can handle the interrupts of babies and children. Whereas men spent more time out concentrating on one task at a time such as hunting.

A sleep expert in England says married couples shouldn't be so determined to sleep together.

Dr Neil Stanley, a sleep expert at the University of Surrey, said: "It's not surprising that people are disturbed by sleeping together.

"Historically, we have never been meant to sleep in the same bed as each other. It is a bizarre thing to do.

"Sleep is the most selfish thing you can do and it's vital for good physical and mental health.

"Sharing the bed space with someone who is making noises and who you have to fight with for the duvet is not sensible.

Once the sex becomes infrequent (or so married men assure me) why not sleep apart some of the time?

Marriage doesn't just make men dumber. It also takes away some of their drive. Previous research has shown that getting married lowers male testosterone and having kids lowers it even further.

Gray studied testosterone in saliva collected from 58 men (48 of them Harvard students) between the ages of 20 and 41. Half were married, and of those, 15 were married with children. He took four saliva samples from each man: two in the morning and two in the evening. The subjects also completed questionnaires about their demographic, marital, and parenting backgrounds. Among other things, the questionnaires asked how much time the men spent with their spouses (instead of hanging out with the guys) on their last day off from work, and measured the effort they expended caring for their children. Analysis showed that marriage, fatherhood, and longer periods spent with wives and children were all linked to lower testosterone levels. Fathers in particular had levels significantly lower than those of unmarried men. Researchers also observed that hormone levels in the morning samples were high and relatively even among the men; the differences appeared at night.

On the other hand, the lower testosterone might reduce the risk of prostate cancer and reduce the general rate of aging.

By Randall Parker    2006 July 23 03:24 PM   Entry Permalink | Comments (6)
2006 January 10 Tuesday
We Really Are Out Of It The First 10 Minutes After Waking

In the first minutes after waking up our brains function worse than when drunk or severely sleep deprived.

A new University of Colorado at Boulder study shows that people who awaken after eight hours of sound sleep have more impaired thinking and memory skills than they do after being deprived of sleep for more than 24 hours.

The study showed test subjects had diminished short-term memory, counting skills and cognitive abilities during the groggy period upon awakening known as sleep inertia, said CU-Boulder Assistant Professor Kenneth Wright, lead study author. The new study has implications for medical, safety and transportation workers who are often called upon to perform critical tasks immediately after waking, since cognitive deficiencies following 24 hours of sleep deprivation have previously been shown to be comparable to the effects of alcohol intoxication, he said.

The study appears in the Jan. 11 issue of the Journal of the American Medical Association. Study authors included Wright and Adam Wertz of CU-Boulder's integrative physiology department and Joseph Ronda and Charles Czeisler of Brigham and Women's Hospital in Boston, which is affiliated with Harvard Medical School.

"This is the first time anyone has quantified the effects of sleep inertia," Wright said. "We found the cognitive skills of test subjects were worse upon awakening than after extended sleep deprivation. For a short period, at least, the effects of sleep inertia may be as bad as or worse than being legally drunk."

Following six nights of monitored sleep lasting eight hours per night, the study participants were given a performance test that involved adding randomly generated, two-digit numbers, said Wright. Based on the results, the researchers concluded the subjects exhibited the most severe impairments from sleep inertia within the first three minutes after awakening, he said.

The most severe effects of sleep inertia generally dissipated within the first 10 minutes, although its effects are often detectable for up to two hours, according to the study authors.

Studies conducted by Dr. Thomas Balkin and colleagues at the Walter Reed Army Institute of Research in Washington, D.C., have shown cortical areas of the brain like the prefrontal cortex take longer to come "on-line" following sleep than other areas of the brain, Wright said. The prefrontal cortex is thought to be responsible for problem solving, emotion and complex thought.

People who have to suddenly do critical work upon waking are prone to making potentially lethal mistakes in those first minutes.

The CU-Boulder study has implications for medical professionals who are often called on to tend patients in crisis on a moment's notice, often at odd hours, Wright said. Medical residents, for example, who may work 80 hours or more per week and who "catnap" at times, could be prone to make simple math mistakes when calculating dosages of medicine during bouts of sleep inertia, he said.

The results also have implications for emergency medical technicians and firefighters who may be hastily awakened and called upon to drive a vehicle to an emergency scene, putting themselves and others at risk, said Wright. The study also has implications for commercial truck drivers, who frequently pause for quick naps in their vehicles' sleeping berths during cross-country excursions, he said.

We should avoid having intellectually difficult problems to solve upon awaking. We should also structure our immediate environments around beds to not require any great cognitive effort to safely navigate.

By Randall Parker    2006 January 10 10:10 PM   Entry Permalink | Comments (11)
2005 June 06 Monday
High Schools Disrupt Natural Teen Sleep Schedules

When I was in grade school and high school I always wanted to stay up later and sleep later than school schedules allowed. My mind was always better later in the day and in the evening. Well, a new study vindicates by feeling at the time that school was not set up for my circadian cycle. Kids are being forced wake up and get going about 2 hours too early.

Current high school start times deprive adolescents of sleep and force students to perform academically in the early morning, a time of day when they are at their worst, according to a study in the June issue of the journal Pediatrics.

Results from high school senior sleep/wake diaries kept for the study also showed that adolescents lost as much as two hours of sleep per night during the school week, but weekend sleep times during the school year were similar to those in summer.

Advanced placement biology students were recruited for the study. So the kids do not sound like they were slackers.

The study was a collaborative project involving researchers at the Feinberg School of Medicine and the Center for Sleep and Circadian Biology at Northwestern University and faculty, students and parents from Evanston Township High School, Evanston, Ill. The students were advanced placement biology students who helped conduct the study and analyze the collected data.

Martha Hansen, advanced placement biology teacher and current science department chair at Evanston Township High School, headed the project in collaboration with Margarita L. Dubocovich, professor of molecular pharmacology and biological chemistry and of psychiatry and behavioral sciences, Feinberg; and Phyllis C. Zee, M.D., professor of neurology, Feinberg.

The study assessed the impact of sleep loss after the start of school on cognitive performance and mood and examined the relationship of weekday to weekend sleep in adolescents.

The study also showed that

exposure to bright light in the morning did not modify students' sleep-wake cycle or improve daytime performance during weekdays probably because of their strict school schedule. All students performed better in the afternoon than in the morning.

Students in early morning classes reported being wearier, less alert and having to expend greater effort. Potential solutions to this problem could be solved by changing school start times and by giving standardized tests later in the day, the authors suggested.

For example, classes at Evanston Township High School start at 8:05 a.m. and run until 3:35 p.m. – one of the longest school days in Illinois. Many high schools in the country have start times of 7:15 or 7:30 a.m. In addition, almost all standardized tests in high school begin at 8 a.m.

Since this is when adolescents show their poorest performance levels, a change is clearly needed and would be relatively easy to negotiate, the researchers suggest.

Technology should be used to allow kids to adjust their learning schedules to their body's circadian rhythms. The use of pre-recorded high quality and high resolution lectures would allow kids to watch lectures on difficult subjects when their minds feel keen enough to handle difficult material. Our current regimented method of marching kids through a series of fixed time length classes strikes me as a hold-over from the factory era. Lecture delivery could be done electronically at any time of the day or night. A kid who has a hankering to just listen to hours of biology on one day and hours of history on another day ought to be able to do that as long as all the needed material is viewed. Or if the kid wants to watch physics lectures only after 9 PM then make it easy to do so.

I can even picture electronic methods to detect whether each kid paid attention to n hours of biology lectures and m hours of calculus lectures. Biometric scanning equipment attached to a device that plays lecture videos could track whether each kid has watched each lecture. Or kids could have to set for automatically delivered tests to monitor their progress.

Kids could even win greater flexibility in the use of their time by meeting testing goals. A kid who manage to, say, test as being a month ahead of schedule could be allowed to spend more hours listening to music, watching movies, playing video games, or other activities. We should make education less like a planned regimented socialist economy and give kids ways to earn the ability to exercise greater control of their time. I bet many kids would learn more rapdily and also be happier about learning.

By Randall Parker    2005 June 06 12:28 PM   Entry Permalink | Comments (29)
2005 April 17 Sunday
SleepSmart Headband Alarm Clock Wakens You From Light Sleep Stage

A company called Axon Sleep Research Laboratories has developed a headband alarm clock that awakens you when you are not in a deep stage of sleep.

Have you ever felt that you have had a full night’s sleep, but you still feel tired when your alarm rings? When we sleep, we repeatedly move through several cycles of brain activity. It is incorrectly believed that an extra 15 minutes of sleep would make us feel better. What actually makes us feel alert and energetic, however, is being awoken out of the right sleep cycle.

The scientific community has known about this phenomenon for decades, but the technology has not existed to take advantage of it — until now. Enter SleepSmart: an intelligent alarm clock that monitors your sleep cycles as you sleep, waking you at the ideal moment from the optimal stage of sleep. This optimal moment might be several minutes prior to your set alarm time. However, when you wake up, you will be refreshed and ready for action — just as if you had awoken naturally.

The device is worn on your head and it analyses your EEG brain wave to decide when to awaken you. The device does not appear to be on sale yet.

They claim that being awakened from a lighter stage of sleep will cause a person to feel less tired.

SleepSmart’s technology is based on the existence of sleep cycles. For the sake of simplicity, we will classify the cycles into 3 categories: light, deep and REM (rapid eye movement) sleep. Recent scientific research has learned that the way one feels after waking up is determined not by the length of sleep, but rather the sleep cycle from which that person awakens. When awoken from deep sleep, the sleeper feels groggy, tired, and grumpy. However, if someone wakes up from a lighter stage of sleep, no matter how many hours they slept, they still wake up recharged, invigorated, energetic and alert.

SleepSmart capitalizes on this finding by waking people only from light sleep. In order to do this, users wear a soft headband that passively monitors the brain. The end result is the aversion of sleep inertia and the production of a more energetic, attentive and happy morning.

The headband is the idea of a group of Brown University students.

By Randall Parker    2005 April 17 03:19 PM   Entry Permalink | Comments (9)
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