MONDAY, March 7 (HealthDay News) -- Sleep tight, but not right after looking at something bright.
That's the message of a new survey that suggests many Americans might be losing valuable shut-eye because they spend the hour before bedtime in front of the electronic glow of a television, cell phone or computer.
The survey doesn't prove that exposure to bright light before bed disrupts sleep. But some experts recommend an "electronic curfew" an hour before bedtime, when people should dim lamps and avoid checking their e-mail or watching late-night TV.
"Falling asleep isn't like flicking a switch. We don't put our heads on the pillow and fall off to sleep," said Allison G. Harvey, a sleep specialist and professor of psychology at the University of California at Berkeley. "We take time to wind down at night. If we've got bright light conditions, we're not giving ourselves a chance to get off to sleep and stay asleep."
The National Sleep Foundation's annual Sleep in America poll, whose results were released Monday, surveyed 1,508 people between the ages of 13 and 64.
Overall, the survey suggests that a majority of Americans aren't getting enough sleep: 63 percent said their needs aren't being met during the week.
Ninety-five percent of those surveyed said they'd used an electronic device -- such as a television, computer, video game or cell phone -- within the hour before bed at least a few nights a week. About two-thirds of people aged 30 to 64 frequently watch TV in the hour before bed, but only about half of younger people do. Not surprisingly, those under 30 are much more likely than older people to send or receive text messages on their cell phones in the hour before bed.
The problem is that light exposure before sleep can disrupt body rhythms and suppress the release of the hormone melatonin, which promotes sleep, Harvey explained.
But does it actually hurt sleep? Harvey said the survey doesn't prove that. Still, she suspects exposure to light is a problem. "No one's proven it yet, but it seems more than tempting to speculate fairly strongly," she noted.
Dr. Matt Travis Bianchi, a sleep specialist at Harvard Medical School in Boston, said the issue of light before sleep is complicated: not all kinds of light activate body cycles in the same way, and a little bit of light -- such as from a TV at a distance -- might still cause a problem.
Also, "we are very different in our sensitivity to light," he added. "I have on rare occasions had patients who were 'light-toxic,' in that if they got bright light late at night they couldn't sleep at all. Contrast that with patients I have who sleep with the light and TV on routinely, and don't have much problems that they can feel."
What can people try to do to sleep better?
Harvey recommends an electronic curfew. Also, "try to stick to a fairly regular wake time, get bright light in the morning and dim light at night, exercise regularly and have a bedtime routine of 30 to 60 minutes when you're letting yourself wind down," she suggested.
If you don't sleep well but can't bear to tear yourself away from the TV or computer before going to bed, Bianchi recommends trying a pair of "dampening glasses," which will filter out the most damaging light. You can try them, he said, and see if they make a difference.
He also said people should be aware that it may not be the light of a cell phone or computer that triggers sleep problems. It could be the anxiety produced when you, say, read an e-mail that makes you angry.
For more about understanding sleep, try the U.S. National Institute of Neurological Disorders and Stroke.
SOURCES: Allison G. Harvey, Ph.D., professor, psychology, and director, The Golden Bear Sleep and Mood Research Clinic, University of California, Berkeley; Matt Travis Bianchi, M.D., Ph.D., instructor, neurology, Harvard Medical School, Boston; March 7, 2011, National Sleep Foundation 2011 Sleep in America Poll
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