July 19, 2011
Circadian Clock Signal Weakens With Age

A pair of collections of cells known as the suprachiasmatic nucleus at the base of the brain in the hypothalamus regulate the body's circadian rhythm as the sun goes up and down. As we age those cells do a poorer job of putting out a wave signal that orchestrates the complex mechanisms that make us wake up and go to sleep.

A new study of the brain's master circadian clock — known as the suprachiasmatic nucleus, or SCN — reveals that a key pattern of rhythmic neural activity begins to decline by middle age. The study, whose senior author is UCLA Chancellor Gene Block, may have implications for the large number of older people who have difficulty sleeping and adjusting to time changes.

Can't sleep as well as you get older? A really small number of cells is at fault. Imagine how much better you'd sleep if several thousand cells could get rejuvenated or replaced.

Sleep quality declines as people age. This is yet another reminder: aging sucks. Really. Totally. There's no upside.

"Aging has a profound effect on circadian timing," said Block, a professor of psychiatry and biobehavioral sciences and of physiological science. "It is very clear that animals' circadian systems begin to deteriorate as they age, and humans have enormous problems with the quality of their sleep as they age, difficulty adjusting to time-zone changes and difficulty performing shift-work, as well as less alertness when awake. There is a real change in the sleep–wake cycle.

This result reminds me of the vicious cycles that drive much of aging. Deterioration of sleep quality reduces the repair that happens to the body as we sleep. This accelerates aging, including aging of components that regulate sleep.

With age the signal level from the SCN does not go down as far at night.

"In the middle-aged mice, they still have a circadian rhythm, but the amplitude is reduced," Block said. "During the nighttime, when electrical impulse activity levels are usually fairly low, the levels have increased. Thus, the difference between the highest levels of activity during the daytime and the lowest levels of activity during the nighttime is much smaller in the middle-aged mice."

We need a way to do periodic service on the SCN. Replace some worn out neurons and support cells perhaps. But that's going to be tricky to do in a highly targeted way. Another recent report shows that neural stem cells need a supporting cell type to enable them to replicate. Creating a local environment with the right supporting cells orchestrated to do the needed repair operations might turn out to be very difficult. Will it be enough to get the right cell type delivered to the right area? Or will 3-D scaffolding on a miniature scale be needed?

Share |      Randall Parker, 2011 July 19 09:24 PM  Aging Brain Studies

PacRim Jim said at July 20, 2011 1:59 AM:

What doesn't weaken with age?

cathy said at July 20, 2011 5:28 AM:

I've read surveys that say older people are happier than younger people. I know that I am happier at 63 than I was at 33, so that doesn't suck.

JP Straley said at July 20, 2011 7:55 AM:

Would the use of melatonin supplements compensate for the natural decrease in hormonal control of the sleep cycle?

JP Straley

fb0252 said at July 21, 2011 11:16 AM:

sleep does not deteriorate with age provided the causes of sleeplessness are understood. insomnia of the normal sort is caused by mild (though very noticeable in terms of sleep prevention) distress emanating from the lower digestive track but likely the result of inflamed (mildly distressed) nerves emanating to the sleep-relaxation centers of the brain. as experiement take a laxative at any age and empty out before bed and you sleep like a baby. nobody believes this but it works. cause and effect. remove cause of distress and u sleep. similarly--when distress present u r unable to count to 10 sheep. if distress gone, you count to 10 and fall asleep, and generally stay asleep.

solaris said at July 21, 2011 11:34 AM:

"I know that I am happier at 63 than I was at 33"

Perhaps that's a sign that your brain has deteriorated?

Just kidding!

Mrs. Davis said at July 21, 2011 12:47 PM:

Is this a feature or a bug?

TTT said at July 21, 2011 1:02 PM:

What doesn't weaken with age?

Self-control and long-term thinking.

willis said at July 21, 2011 1:36 PM:

Glenn Reynolds comments: "This may have been group-adaptive in the old days, though. Old people — too weak to do the hard day’s work — were up at night when the workers were sleeping, meaning that someone was more likely to notice marauding enemies, dangerous animals, fires, etc. Now, not so much."

Not true, old folks with poor sleeping habits stay awake and watch Obama speeches, then warn the rest of us.

Randall Parker said at July 21, 2011 6:12 PM:


Think of it this way: Has the aging of your body made you happier? Or has your happiness come from unrelated changes in your ways of thinking and in your circumstances? If your body was just as young now as it was at age 33 would you be any less happy?

Older people who suffer from arthritis, slipped disks, blindness, and other disabilities are not happier.


The ability to think deteriorates. At some point that impacts ability to do long-term thinking. Demented people often undergo personality changes.

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