Tired brains may enter sleep mode while awake

USA Today, April 29, 2011 on page 4A describes new research in Nature "The brains of rats kept awake past their bedtimes begin to turn themselves off even though the rat is still awake…it's likely that sleep-deprived human brains respond the same way…Long before signs of yawns and trouble keeping focused, it's probably already happening on a localized scale in the brain and have consequences on performance…[Rats kept up four hours past the time they would normally be asleep] were awake but individual neurons in their brains turned themselves off. The shutdown is why the rats did progressively less well on a task…There's no reason to think this does not happen in the human brain…At a certain point, they start saying, I've had enough, I'm going off-line…as you stay awake longer, your cells start to drift into sleep and your performance starts to go down, which could provide an explanation as to why we function less well the longer we've been awake…the message is you need to take sleep very seriously. When you're starting to nod off, it's too late. Even before that, there may be impairment. Respect your need for sleep."

This is the explanation for loss of impulse control (the "witching hour") near the end of the day in children short of sleep and the observation that well-rested children are more focused and cooperative. During the day, having a brain with a full set of neurons (nerve cells) firing when awake is better than a brain with some neurons taking a siesta.

Marc

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