SUNDAY, Jan. 31, 2010 (HealthDay News) -- Get enough sleep -- whatever that means for you -- and you're likely to ace that test, think more creatively, have better long-term memory and preserve important memories.
That's the bottom line behind a spate of recent studies.
But why sleep has those effects and how that information can be used to your advantage are questions still under study, said Dr. Robert Stickgold, an associate professor of psychiatry at Harvard Medical School and director of the Center for Sleep and Cognition at Beth Israel Deaconess Medical Center in Boston.
"The sleeping brain is not stupid," said Jessica Payne, an assistant professor of psychology at the University of Notre Dame in Indiana, who has researched the effect of sleep on memory. "It's smart, and it's making sophisticated decisions about which memories are important and should be held onto."
Yet why sleep is so crucial for memories remains a big mystery, Payne and Stickgold agreed.
"It turns out we are not like TiVo," Stickgold said, comparing humans to the video recording device. "TiVo is good at recording one station while it shows you another. We can't do that. We can't simultaneously take in information and process it."
Rather, he said, sleep helps in the whole information-processing part of the picture. "It might be that sleep is an amount of time to give the brain a chance to go offline and shift into a different psychological mode that's evolved to perform certain types of memory processing," Stickgold said.
Though there's still much to be learned, he said, research suggests that REM sleep -- the stage of sleep involving rapid eye movement -- seems to be the phase that resolves the issue, or tells you what to do with new information.
Someone who can't decide whether to take a new job, Stickgold said, rarely says, "I'll go out for a hamburger." More often, they opt to sleep on it.
In her research, Payne said, she's found that a good night's sleep can lead to better inferential ability. In other words: "You may learn about a concrete relationship between A and B and B and C, but you don't see there might be an A and C connection," she said. "Our evidence suggests that when you sleep, you learn the hierarchy of information, you learn to extract the more sophisticated relationships."
"Sleep is not only important for your ability to remember," she said, "but it also helps you be more creative, find more interesting and distant connections and be more innovative."
As for how to convince us that a good night's sleep is a worthy goal? Payne said her list of pluses usually does it. People are tired of hearing, "Take this pill" or "Try this" to improve memory, she said.
But when they hear that a good night's sleep comes with such substantial benefits, they listen, she said: "Everyone wants to be more creative, more innovative."
Stickgold said that no one has "come up with the right ad campaign yet" to convince people to get enough sleep. Perhaps a good one, he joked, would be this: "If you aren't getting enough sleep, you will become sick, fat and stupid."
In truth, he said, sleep deprivation has been linked with obesity because it disrupts insulin regulation, in turn easing weight gain. And the sleep-and-illness and sleep-and-memory links are well known.
Though the amount of sleep needed does vary, Stickgold has an easy test to decide if you're getting enough. "Watch what happens on the weekend if you don't set an alarm," he said. "If you sleep more than you sleep during the week, you aren't getting enough sleep."
He said that someone he recently spoke with was in a car accident caused by drowsy driving. His suggestion: "Try for one week to sleep for eight hours a night and see if things get better or worse."
Stickgold suspects that anyone who does this will find that lots of daily tasks -- driving and checkbook balancing among them -- will become easier. And along with that might come the realization that getting an extra hour or two of sleep a night can pay big -- and perhaps even life-saving -- benefits.
More information
The National Sleep Foundation has more on how much sleep people need?
