E-Readers May Negatively Impact Your Sleep After Reading

You may want to put down that e-reader. Scientists have found that the use of a light-emitting electronic device (LE-eBook) just before bed can negatively impact overall health, alertness, and your circadian clock.

"We found the body's natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices," said Anne-Marie Chang, one of the researchers, in a news release. "Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock and reduced next-morning alertness than when reading a printed book."

Previous studies have actually shown that blue light suppresses melatonin and impacts the circadian clock. That's why scientists decided to see if technology, which uses blue light, could also affect sleep.

In this case, the researchers conducted a two-week inpatient study. Twelve participants read LE-eBooks on an iPad for four hours before bedtime each night for five nights. Then, this was repeated with printed books.

The researchers found that those reading the iPad took longer to fall asleep. In addition, the iPad readers had reduced secretion of melatonin, a hormone which usually rises in the evening and plays a role in inducing sleepiness.

"In the past 50 years, there has been a decline in average sleep duration and quality," said Charles Czeisler, one of the researchers, in a news release. "Since more people are choosing electronic devices for reading, communication and entertainment, particularly children and adolescents who already experience significant sleep loss, epidemiological research evaluating the long-term consequences of these devices on health and safety is urgently needed."

The findings are published in the journal Proceedings of the National Academy of Sciences.

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