What Your Sleeping Style Says About You (cont.)

Idzikowski's more recent research is again focusing on preferred positions and is cross-cultural to see if these initial findings hold. "The original United Kingdom data is compared with data collected from Australia, Japan, Hong Kong, China, and Singapore," he says. "The cross-cultural work has raised more questions."

One thing is clear, however. "If you sleep in a bad position, you're more likely to be grumpy the next day," he says.

According to his initial data, if you sleep like a log, at least positionally, you are typically easy going, sociable, and want to run with the A-list crowd. As a result, however, you may be gullible. People who sleep on their side with both arms out in front can be suspicious and cynical.

And if you know anyone who sleeps on their back with both arms up around the pillow (a.k.a. the "starfish"), you are in luck because such sleepers make good friends. They are always ready to listen and offer help.

Even a 'Starfish' Can Snap

But even a starfish can turn on you if they don't get enough sleep, experts tell WebMD

Sleep has "a huge effect on our personality and well-being because everyone has an individual need to sleep and if you are not able to meet your needs, you are not going to behave," says Ana Krieger, MD, director of the New York University Sleep Disorders Center in New York City. "Your normal way to compensate for the loss of sleep is by overworking, being rude or hyperactive, being more depressed and less social."

"With regard to personality, everybody knows that one of the first consequences of sleep deprivation is impaired sustained attention and irritability," says Mark W. Mahowald, MD, director of the Minnesota Regional Sleep Disorders Center at Hennepin County Medical Center and professor of neurology at the University of Minnesota in Minneapolis. "Just about any degree of sleep deprivation will result in irritability and has far-reaching ramifications in the workplace, family, classroom, and behind the wheel."

By contrast, delaying start times in schools so students get more sleep results in better behavior, he points out. "With more sleep, people are less irritable and less short tempered."

"Most of the studies show that when a person doesn't get enough sleep on a regular basis, there is a gradual deterioration of function, and the same thing is true if you disrupt sleep with lights, sounds, and bells," says Robert Ballard, MD, medical director of the sleep disorders program at National Jewish Hospital Medical Research Center in Denver.

But with adequate sleep, he says, there may be improvement in learning, memory, and reasoning. "People are capable of thinking more abstractly, better capable of problem solving, have improved fine motor coordination and long and short-term memory."

"What we know is that if people don't get as much sleep as they should, they have changes in their mood and their level of activity," agrees NYU's Krieger. For example, when kids get hyperactive and cranky, it means they are overtired and ready for a nap. "Adults just get moody and upset with everybody," she explains.