Brain rewinds, makes itself fresh when you sleep

And when you won't get enough sleep, the brain cannot make itself ready for more and new information, making you an irritable and inefficient person, claimed the researchers from the University of Wisconsin-Madison.

Psychologist Giulio Tononi, who led the study, said brain wave activity is particularly strong during sleep -- a sign that the brain is "wiping out" unnecessary impressions.

The brain literally "unwinds" during sleep -- wiping itself clean in much the same way as a computer reboots, Tononi said.

"Sleep may be the price you pay so your brain can be plastic the next day," he was quoted as saying by the Daily Mail.

Tononi's pioneering research into sleep -- using human volunteers, rats, and computer simulations -- is considered to offer some of the first insights into the 'purpose' of sleep His understanding of the brain and how it "rewires" itself may also lead to a deeper understanding of what consciousness itself is.

His hypothesis is that sleep allows the brain to regroup after a hard day of learning by giving the synapses, which increase in strength during the day, a chance to damp down to baseline levels This is important because the brain uses up to 80 per cent of its energy to sustain synaptic activity.

Sleep may also be important for consolidating new memories, and to allow the brain to "forget" the random, unimportant impressions of the day, so there is room for more learning the next day.

This could be why the brain waves are so active during certain periods of sleep, Tononi said.

"While there may still be no consensus on why animals need to sleep, it would seem that searching for a core function of sleep,particularly at the cellular level, is still a worthwhile exercise," he concluded.