Researchers have recommended that couples banish cellphones from the bedroom, thanks to the dark allure of their constant dings and alerts. Now add another item to that list of forbidden devices: the humble e-reader.
A new study suggests that reading from a light-emitting electronic device like an iPad or iPhone has an adverse affect on sleep, as compared to reading a traditional printed book.
“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,” says Anne-Marie Chang, author of the study and an associate neuroscientist at Brigham and Women’s Hospital, a teaching affiliate of Harvard Medical School. “Participants reading a [light-emitting] 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.”
To conduct the two-week in-patient study, Chang and her team recruited a dozen participants who read for four hours each night before bed. During the first week, half of the participants read using iPads and half read using printed books. Then, during the second week, they switched. The iPad readers took longer to fall asleep, and were drowsier the next day.
Prior research has established strong links between light and sleep/wake patterns. Doctors are still grappling to understand the impact of screen time on sleep and health, amid a backdrop of widespread sleep deprivation. According to a survey conducted by the Centers for Disease Control and Prevention, one in three Americans sleeps less than the recommended minimum of seven hours per night.
“In the past 50 years, there has been a decline in average sleep duration and quality,” says Charles Czeisler, chief of the hospital’s Division of Sleep and Circadian Disorders. “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.”