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By Dennis Kleinman, HealthAtoZ contributing writer
"Get a good night's sleep." That's still the best advice, according to studies that show sleep deprivation has an impact on memory.
Our modern pace of living has eroded our sleep time and could be seriously "short-changing our education potential," says Robert Stickgold, Ph.D., an assistant professor of psychiatry at Harvard Medical School.
While in the laboratory, sleep-study volunteers improved their simple performance tasks by 20 percent after one night's sleep after training. Even musicians (such as pianists) relate that "sleeping on a tune" can help their performance, with extra sleep on successive nights enhancing their skills.
Don't make it all night
On the other hand, students who pull "all-nighters" and cram for exams ultimately weaken long-term memory and performance over time. This was shown in a study of task-learners who were kept awake the first night after their training. The study participants went right back to their beginning levels of performance when they were measured the following day, even two days later after catching up on their sleep.
It's simple, Stickgold says. How well you do at some things doesn't depend on where you went to school or what your parents do for a living. It just depends on how well you sleep at night.
Dreamtime learning
Even the different sleep cycles affect different types of learning. For example, doing well on visual tests requires relaxed slow-wave sleep similar to that found in the beginning of a sleep cycle, and rapid eye movement (REM) sleep (when we dream) in the last part of a cycle. Movement and coordination tests rely more on non-sleep cycles found later in sleep, before we dream.
Apparently, researchers have gained some revelations from the animal kingdom. Daniel Margoliash, Ph.D., professor in the Department of Organismal Biology and Anatomy at the University of Chicago, found that young birds might actually rehearse their new songs while they sleep. By measuring the activity in brain cells involved in learning a new song, Margoliash found that the same cells were active during the birds' sleeping or napping activity.
Rats also rehearse maze running in their sleep, reviewing the characteristics of their motion during the day while sleeping at night, according to the findings of Matthew Wilson, a researcher at the Massachusetts Institute of Technology.
"Just like our own dreams, the replay can be recognizable but warped; some events are stretched out over time and others never really happened," Wilson says. He believes this indicates that our new experiences are generalized and re-evaluated during sleep.
Are you sleeping?
A sleep poll by the National Sleep Foundation (NSF) found that one-quarter of American adults, or 47 million people, aren't getting the minimum amount of sleep they need at night to be alert the following day, resulting in what appears to be an epidemic of daytime sleepiness that can impact not only cognition but also performance and state of mind.
The survey also revealed that Americans who get too little sleep are downright cranky. They're more apt to sit and seethe in traffic jams, quarrel with others or overeat.
"Scientists have documented the link between sleep deprivation, mood, and performance in the lab before. But this poll is the first large-scale view of the extent to which insufficient sleep plays out in the real world each day," says James K. Walsh, Ph.D., who is executive director and senior scientist at St. Luke's Hospital Sleep Medicine and Research Center in Chesterfield, Missouri. The conclusions of the poll were:
- Those who got less than six hours of sleep on weekdays were more likely to say they were tired than those getting more than 8 hours of sleep and more likely to describe themselves as stressed.
- People who reported being sleepy during the day were more likely to describe themselves as dissatisfied with life and angry, compared with those who were rarely or never sleepy during the day.
- On the flip side, the less people experienced insomnia, the more likely they were to describe themselves as "full of energy, relaxed and happy."
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External Sources
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American Association for the Advancement of Science, Boston, 2002
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National Sleep Foundation's 2000 Sleep in America Omnibus Poll
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Massachusetts Institute of Technology
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Reports from the Laboratory of Neurophysiology, Department of Psychiatry, Harvard Medical School: Visual discrimination learning requires sleep after training, Visual discrimination task improvement: A multi-step process and occurring during sleep, and, Watching the sleeping brain watch us - sensory processing during sleep.
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The mind in REM sleep: reports of emotional experience. Fosse R, Stickgold R, Hobson JA. Institute of Psychology, University in Oslo, Norway
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St. Luke's Hospital Sleep Medicine and Research Center in Chesterfield, Missouri
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This article was reviewed and updated June 2007.
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