The National Sleep Foundation (NSF) is warning people that they should turn off electronic gadgets an hour before bedtime, following a survey showing that they can keep you awake at night.
According to the 2011 Sleep in America poll, 43 percent of Americans between the ages of 13 and 64 say they rarely or never get a good night's sleep on weeknights. Three-fifths say they experience a sleep problem every night or almost every night.
And they're devoted users of technology in the hour before bed, with 95 percent saying they use television, computer, video game or cellphone. Six in ten say they use their laptops or computers at least a few nights a week within the hour before bed.
"Artificial light exposure between dusk and the time we go to bed at night suppresses release of the sleep-promoting hormone melatonin, enhances alertness and shifts circadian rhythms to a later hour—making it more difficult to fall asleep," says Dr Charles Czeisler of Harvard Medical School and Brigham and Women's Hospital.
"This study reveals that light-emitting screens are in heavy use within the pivotal hour before sleep. 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."
The researchers say they believe that interactive technologies such as video games, cellphones and the internet are more likely to disrupt speep than passive ones such as television or music.
"The hypothesis is that the latter devices are more alerting and disrupt the sleep-onset process," says Dr Michael Gradisar of Australia's Flinders University. "If you feel that these activities are alerting or causing you anxiety, try doing something more 'passive' to help you wind down before bed."