What purpose does sleep serve for the brain?

A. We don't yet know full answer to this fundamental question however neuroscience is providing intriguing clues. It's increasingly clear that adequate sleep is necessary to consolidate certain types of memories and to improve performance on different learning tasks. If we are deprived of sleep, we don't learn as well. Recent brain research indicates that so-called "slow-wave" sleep, a type of non-REM sleep which generally occurs early in the night, is specifically crucial to learning. Sleeping within 30 hours of new learning seems to be essential, however some studies suggest that brief, 60- to 90-minute naps produce as much improvement in practiced behaviors as a full eight hours of sleep, so long as naps include both slow-wave and REM sleep.

Anyone who has ever pulled an all-nighter knows that lack of sleep can impair learning, memory, attention and decision-making, making it difficult to perform even simple tasks. Our risk of accidents is also greater when we don't sleep well. While average person requires about 8 hours of sleep per night, surveys suggest that America is sleep-deprived. As many as one-fifth of us say daytime sleepiness keeps us from performing at our peak, and nearly as many report having fallen asleep during driving. Chronic lack of sleep or abrupt changes in sleep patterns could signal an underlying problem that warrants evaluation by a qualified sleep doctor.