Finding yourself wide awake after a few hours of sleep, or waking often during the night is called "parasomnia" or "sleep maintenance insomnia," and it's much more common than people think. A 2005 National Sleep Foundation poll found that 75 percent of adults frequently have symptoms of sleep dysfunction, including waking during the night.
Just as the victims in slasher flicks make fatal errors (why are you running up the stairs?), we are often our own worst enemies when it comes to a solid night of sleep. "People think that because they're able to fall asleep they'll stay asleep, even if they've had too much caffeine," says Rubin Naiman, Ph.D., a sleep and dream specialist at Andrew Weil's Program in Integrative Medicine at the University of Arizona.