Power naps boost brain

An hour of sleep during the day not only refreshes you, but can actually make you smarter, new research has found.

In addition, researchers have also discovered that the longer you stay awake, the more sluggish your mind becomes.

Researchers from the University of California, Berkeley, studied the performance of young people with different sleep patterns.

Their past research found that the well known practice of "pulling an all-nighter" reduces a student's ability to cram in new facts by nearly 40%, due to a shut-down of brain regions during sleep deprivation.

Now these new findings show that taking a "siesta" during the day increases learning ability compared to students who stay awake throughout the day.

Matthew Walker, lead researcher of the study, commented: "Sleep not only rights the wrong of prolonged wakefulness but, at a neurocognitive level, it moves you beyond where you were before you took a nap."

In the study, 39 healthy young adults were divided into two groups – nap and no-nap. At noon, all the participants had to undertake a rigorous learning task intended to work the hippo-campus, a region of the brain that helps store fact-based memories. Both groups performed at comparable levels.

At 2pm, the nap group took a 90-minute siesta while the no-nap group stayed awake. Later that day, at 6pm, participants performed a new round of learning exercises. Those who remained awake throughout the day became worse at learning. In contrast, those who napped did markedly better and actually improved in their capacity to learn.

Mr Walker suggests that the difference in performance is related to the need of the brain to clear short-term memory storage and make room for new information.

"It's as though the e-mail inbox in your hippocampus is full and, until you sleep and clear out those fact e-mails, you're not going to receive any more mail. It's just going to bounce until you sleep and move it into another folder," Mr Walker said.

It seems that the refreshing effect takes place in the otherwise mysterious stage 2 non-REM sleep phase, which is poorly understood by science even though it takes up around half of our sleeping hours.

"I can't imagine Mother Nature would have us spend 50% of the night going from one sleep stage to another for no reason," Walker said. "Sleep is sophisticated. It acts locally to give us what we need."

The results are presented at the 2010 annual meeting of the American Association for the Advancement of Science.

This article was published on Mon 22 February 2010