"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 Charles Czeisler, PhD, MD, 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."

"My research compares how technologies that are ‘passively received' such as TVs and music versus those with ‘interactive' properties like video games, cell phones and the Internet may affect the brain differently," says Michael Gradisar, PhD, Flinders University (Australia). "The hypothesis is that the latter devices are more alerting and disrupt the sleep-onset process. If you feel that these activities are alerting or causing you anxiety, try doing something more ‘passive' to help you wind down before bed."