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Source: The Society for Neuroscience

Sleep does more than banish dark under-eye circles. It also helps you learn, according to an increasing amount of research in animals and humans. Advances in neuroscience led scientists in recent years to produce a large body of converging evidence that shows that sleep helps secure memories and aids at least some types of learning. The findings indicate that sleep is much more important than commonly believed.

It's 3 a.m. and you're still glued to The Osbournes marathon running on MTV. What's a little less sleep when you can see Ozzy war with the neighbors?

You're not alone. Many Americans skimp on shut-eye. Almost one-third of respondents said they get less than seven hours of sleep per night during the week, according to a recent survey of approximately 1,000 people by the National Sleep Foundation.

A large body of converging research, however, shows that it's time to rethink your priorities. Sleep is more important than many people believe. Specifically, studies find that it helps secure memories and aid learning. These findings are leading to:

A better understanding of how sleep and wakefulness contribute to learning.
Increased respect for sleep and its ability to benefit the brain.
Ways to use sleep to boost learning in healthy individuals and possibly those recovering from brain injuries.
The notion that sleep is important for learning has been kicked around, but hotly debated, by scientists for years. Recently, however, advances in neuroscience led researchers to carry out a variety of careful studies in both humans and animals, which provide clear evidence that sleep is indeed important for at least some types of memory and learning.

In particular it seems to secure memories, termed procedural memories, which help people learn skills. Thanks to procedural memories, you can master a video game, a gymnastics move or a melody on the piano.

In some of the work, researchers trained people to complete a procedural memory-based task and then determined if sleep improved their performance. Several studies show that it does. In one recent example, participants had to repeatedly type a sequence on a keyboard. A group trained in the morning and then tested 12 hours later showed no significant improvement. But a full night's sleep improved their performance by almost 20 percent. Another group, trained in the evening, improved their performance by about 20 percent after a full night's sleep. But after another 12 hours of staying awake, they showed hardly any improvement. This shows that sleep, not time, aids the learning.

Sleep may allow the brain to reprocess newly learned information so that memories of it stick. Research that uses technology to peer inside the brain supports this idea. In one study, scientists first found that sleep improved performance on a task that tests procedural memory. They then used an imaging technique to map brain activity and discovered that some brain areas activated during the training of the task were reactivated during sleep (see illustration).

Studies in animals that look even deeper also find evidence of reprocessing. For example, researchers scrutinized the brain cell activity of rats while they trained to run around a track and while they slept. The activity patterns matched. Also, an examination of brain cell activity in zebra finches indicates that during sleep the birds replay songs in their heads, possibly to help secure the memory of them.

Even a nap in the middle of the day may benefit some learning, according to a recent study. Researchers found that scores on a task that tests procedural memory worsened over the course of four daily practice sessions. Possibly this "burnout" occurs because the brain can only take in so much information before it has a chance to secure the memory of it through sleep. It turned out that a half-hour nap after the second session prevented further deterioration. An hour nap improved performance in later day sessions.

Researchers have plans for a number of other studies that could further solidify sleep's role in learning. They say, however, that already the evidence provides argument enough that it's time to shut off the TV and catch some zzzz's.