In a related project, other Harvard researchers found that a midday nap does much to recharge the system by allowing the brain to consolidate the memories of habits, actions and skills learned during the day, according to Robert Stickgold of the department of psychiatry. A nap, he says, gives the brain a chance to avoid "burnout" and reorganize itself, perhaps bringing new circuits in to relieve some that had grown weary.
That short of a snooze, however, is no substitute for a full night's sleep, the researchers say.
And to be much help at all, the nap needs to be about an hour long. Try explaining that one to the boss.
This is still a relatively new field, and much remains to be learned about what the brain is up to while we think it's just sleeping, but what is emerging loud and clear is the fact that sleep is far more critical than most of us might think.
Sleep = Work
We may think our brain is "dormant" while we're asleep, Walker says, but it's actually firing off commands and doing all sorts of things to restore our biological systems to good working order.
"You spend about a third of your life asleep, and I don't think mother nature is stupid enough to keep you asleep for a third of your life to do just one thing and one thing only," like rest your weary bones, he says.
"You don't spend two thirds of your life awake just doing one thing. You do many things while you are awake."
Researchers are finding, he says, that parts of the brain are as active when we are asleep as when we are awake."
And the new research suggests that if we cut back even a little on our sleep, we're reducing the brain's ability to commit what we have learned to memory, whether it's typing, designing a rocket engine, or learning a new dance step.
It's enough to give you nightmares.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.