A new study has discovered that reading on a tablet or an e-book before going to bed may not be such a good idea.
A group of sleep researchers in Boston found that these devices can keep users up at night and make them sleepy the next morning in a study that is the first to truly analyze how tablets and e-books affect the body's sleep systems, according to Mashable.
"A lot of people think this is psychological," one of the study's authors explained to The Washington Post. "But what we showed is that reading from light-emitting, e-reader devices has profound biological effects."
Participants were asked to read for four hours in the evenings with either an iPad or regular printed book, and then to go to bed at 10 p.m., CBS News reported. The researchers kept track of the participants' melatonin levels, how much they slept and how awake they were in the morning. Melatonin is a hormone that helps keep the sleep cycle under control.
People who read on the electronic tablets were found to have taken 10 minutes longer to fall asleep and had much less REM (rapid eye movement) deep sleep than those who read on paper. The e-reading group also had more trouble waking up the next morning and feeling fully alert, even after sleeping for eight hours.
The bluish light from the devices was believed to affect the brain in a way that kept participants from getting the sleep they needed, with Dr. Charles Czeisler of Brigham and Women's Hospital and Harvard Medical School saying exposure to the light "shifts our circadian rhythms to a later hour, suppresses the release of the sleep-promoting hormone melatonin, and makes it more difficult for us to fall asleep," CBS News reported.
While seven to nine hours is the recommended sleeping time for adults to function at their best, only about 1/3 of U.S. can function with less. Czeisler said a lack of sleep can also put people at a greater risk of cardiovascular disease, obesity and diabetes.
"We live in a sleep-restricted society, in general," said Anne-Marie Chang, assistant professor of biobehavioral health at Penn State and co-author of the study. "It is important to further study the effects of using light-emitting devices, especially before bed, as they may have longer term health consequences than we previously considered."
The study was published Monday in the Proceedings of the National Academy of Science.
