Americans might not be getting enough zzzz’s because they’re watching their TV, cell phone or computer screens an hour before they hit the sack, according to The National Sleep Foundation’s annual Sleep in America poll.

The poll surveyed 1,508 people between ages 13 and 64 about their electronic device usage. Results showed that 95 percent of study participants used an electronic device an hour before their bedtime at least a few nights a week. (Two thirds of the participants, ages 30 to 64, frequently watched television one hour before bed; of those younger, only half watched TV, and those younger than 30 were also more likely to send or receive text messages on their cell phones during this time.)

So how can electronic devices affect sleep? Light exposure before shut-eye can disrupt body rhythms and suppress the release of melatonin, a sleep-promoting hormone, explained Allison G. Harvey, PhD, a sleep specialist and professor of psychology at the University of California at Berkeley.

“We take time to wind down at night,” Harvey said. “If we’ve got bright light conditions, we’re not giving ourselves a chance to get off to sleep and stay asleep.”

While the survey doesn’t prove that electronic gadgets’ glowing screens interfere with sleep, experts suggest people dim the lights and stop checking e-mails and watching TV an hour before they turn in. But people should also remember that sleep problems can also be triggered by reading anger-inducing e-mails or text messages before bedtime.

Still, you can get a good night’s sleep with these tips: Wake up at a usual time, get bright light in the morning and dim lights at night, exercise regularly and allow yourself 30 to 60 minutes to wind down before bedtime.

Click here to learn how sleepless nights also affect childhood obesity.