SAN FRANCISCO (AFP) – A study released on Monday indicated that people in the United States are losing sleep over their gadgets.

All but five percent of people surveyed as part of a National Sleep Foundation poll said they played videogames, watched television, or used smartphones or laptop computers in the hour before going to bed.

"This study reveals that light-emitting screens are in heavy use within the pivotal hour before sleep," said doctor Charles Czeisler of Harvard Medical School.

"Invasion of such alerting technologies into the bedroom may contribute to the high proportion of respondents who reported that they routinely get less sleep than they need."

Being bathed in the glow of monitors or handset screens suppresses the release of sleep-promoting hormone melatonin and enhances alertness, making it more difficult to sleep, according to Czeisler.

The poll showed that 43 percent of people ages 13 to 64 felt they rarely or never got a decent night's sleep during the work week.

Older people were more inclined to watch television while younger people were more likely to opt for computers, smartphones or videogames, according to the survey.

"Over the last 50 years, we've seen how television viewing has grown to be a near constant before bed, and now we are seeing new information technologies such as laptops, cell phones, videogames and music devices rapidly gaining the same status," said Lauren Hale of Stony Brook University Medical Center.

"The higher use of these potentially more sleep-disruptive technologies among younger generations may have serious consequences for physical health, cognitive development and other measures of wellbeing."

Researchers suspected that using smartphones, computers and video game consoles was more stimulating than passively watching television and would make it even harder for people to fall asleep.

Sleep-deprived gadget users were using caffeine and naps to cope with fatigue, according to the poll.