Researchers have found that sleeping for an hour in the afternoon boosts brain power and dramatically increases its ability to learn new facts and tasks.
On the other hand, the more hours we spend awake, the more sluggish our minds become and the less able to absorb new information.
"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," said Professor Matthew Walker, who led the study at the University of California.
The reason was due to a shutdown of parts of the brain regions due to sleep deprivation and the filling up of the short term memory that was usually filed and emptied during periods of sleep.
Scientists have long suspected that there is a link between sleep and memory and have suggested that it acts like a sort of filing system, enabling the brain to distinguish between important and useless information.
In the latest study, 39 healthy young adults were divided into two groups – nap and no-nap.
At noon, all the participants were subjected to a rigorous learning task intended to tax the hippocampus, a region of the brain where fact-based memories are first stored.
Both groups performed at comparable levels.
At 2 pm, the nap group took a 90-minute siesta while the no-nap group stayed awake. Later that day, at 6 pm, 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.
These findings reinforce the researchers' hypothesis that sleep is needed to clear the brain's short-term memory storage and make room for new information, said Prof Walker.
Prof Walker said that fact-based memories are temporarily stored in the hippocampus before being sent to the brain's prefrontal cortex, the filing cabinet of the mind.
"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,” said Prof Walker.
“It's just going to bounce until you sleep and move it into another folder.”
In the latest study, Prof Walker and his team have broken new ground in discovering that this memory- refreshing process occurs when nappers are engaged in a specific stage of sleep.
Electroencephalogram tests, which measure electrical activity in the brain, indicated that this refreshing of memory capacity is related to Stage 2 non-Rapid Eye Movement (REM) sleep, which takes place between deep sleep (non-REM) and the dream state known simply as REM.
Previously, the purpose of this stage was unclear, but the new results offer evidence as to why humans spend at least half their sleeping hours in Stage 2, non-REM, Prof Walker said.
"I can't imagine Mother Nature would have us spend 50 percent of the night going from one sleep stage to another for no reason," Prof Walker said. "Sleep is sophisticated. It acts locally to give us what we need."
Prof Walker and his team will go on to investigate whether the reduction of sleep experienced by people as they get older is related to the documented decrease in our ability to learn as we age.
Finding that link may be helpful in understanding such neurodegenerative conditions as Alzheimer's disease, Prof Walker said.
Sleep is the best thing on all leaving thing and a wonderfull creation of all mighty.
