Reading from tablets could keep you awake longer than print books, warns new study
BOOK worms who read from tablet devices could find themselves being kept awake longer than those reading print, warned a new study.
Researchers have claimed the use of light emitting devices, such as iPads, immediately before bedtime has a powerful effect on the body's natural sleep pattern.
They claim the so-called blue light from tablets impacts overall health, alertness and the body's natural clock which synchronises the daily rhythm of sleep - leaving eBook readers stirring long after putting their novel down.
Author Doctor Anne-Marie Chang, an associate neuroscientist at Brigham and Women's Hospital in the United States, said: "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.
"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 than when reading a printed book."
During a two-week study, 12 people read eBooks on an iPad for four hours before bedtime each night for five consecutive nights.
This process was repeated with printed books, and the order randomised with some reading the iPad first and others reading print first.
The study showed participants reading on the iPad took longer to fall asleep and were less tired in the evening.
They also found electronic readers had reduced secretion of melatonin, a hormone which plays a role in inducing sleepiness.
The reduced melatonin levels also indicated a delayed circadian rhythm, a system which regulates sleep, of more than an hour.
Participants reading a light-emitting eBook took longer to fall asleep and had reduced evening sleepiness
But the effects of reading from tablets were not just limited to night time.
Participants who read from the iPad were less sleepy before bedtime, but sleepier and less alert the following morning after eight hours of sleep.
Although iPads were used in this study, researchers also measured other eReaders, laptops, cell phones, LED monitors, and other electronic devices, all emitting blue light.
Doctor Charles Czeisler, chief of Brigham and Women's Hospital's Division of Sleep and Circadian Disorders, said: "In the past 50 years, there has been a decline in average sleep duration and quality.
"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 of this study were published in the Proceedings of the National Academy of Sciences.
