January 08, 2008
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.

Share |      Randall Parker, 2008 January 08 11:33 PM  Brain Sleep


Comments
cathy said at January 9, 2008 5:18 AM:

I wonder if the fact that old people don't sleep as well as the young might contribute to their worse memory (noted a couple posts down). When I retire I plan to try 'polyphasic' sleep - can't do it now because napping is frowned upon in my workplace.

Randall Parker said at January 9, 2008 5:02 PM:

Cathy,

Yes, I have wondered the same thing. So many things that go wrong with age feed on each other in vicious cycles. Poor sleep quality reduces the repair that happens during sleep so that more damage accumulates.

I want cures for aging. Enough with all this accumulated damage. I've decayed quite enough already. Time to turn it around. I want my 20:15 vision back. It was very handy.

Cedric Morrison said at January 10, 2008 12:47 AM:

I found this interesting:

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.

I take it to mean that one should try to learn no more than one new physical skill per awake period.

Dragon Horse said at January 10, 2008 10:27 AM:

I didn't need a study to know this.

When I was an undergrad and in grad school I could easily tell I retained more information after studying and napping then just straight studying and putting the book down and coming back.

This is also true with motor skills. I found that when playing a video game for the first time that took dexterity, the next day I could play so much better after sleeping. It is almost as if my body mapped the new information while I slept.

Randall Parker said at January 10, 2008 5:24 PM:

Cedric,

That's my interpretation as well.

To state what then becomes the obvious: Every day is another opportunity to learn something in order to give your sleeping mind something useful to process. Don't concentrate more learning hours in fewer days. Spread the learning hours out over all the days in the week so that every night your brain's sleeping hours are not wasted.

Dragon Horse,

I've at least suspected this in the past. But nowadays I can't make practical use of this info. I can't take naps while at work. Maybe I could try afternoon naps on the weekend after some useful book reading.

Dragon Horse said at January 10, 2008 6:47 PM:

Randall:

Yes, I can no longer take advantage of this either. I sleep on average 6 hours a night...too little. Weekends are fine, but I think 5 days of sleeping less than 7-8 hours actually causes some damage or maybe does not allow damage to heal. I have also noticed that since I have got older my ability to memorize and recall has gotten slower, and I am only 30. It is definitely slower than when was I was 21. When this happens I think that my grandmother (84) is starting to show signs of Alzheimer. My wife has no history of dementia in her family and like most Japanese they are long lived. My family tends to live in their early 80's but have all types of chronic diseases. Only 1/4 grandparents has developed signs of dementia though. It is scary.

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