Using smartphones and tablets during the evening is thought to disturb sleep and even damage general health.
But now researchers have found that adequate light during the day can counter the effect.
Researchers at Uppsala University in Sweden found that evening readers of an illuminated ebook device (like the iPad) slept just as well as long as they were exposed to bright light during the day.
Ms Frida Rångtell, the study’s first author, said:
“Our main finding was that following daytime bright light exposure, evening use of a self-luminous tablet for two hours did not affect sleep in young healthy students.”
It is the blue light from e-readers, tablets and smartphones that is thought to cause sleep problems.
Previous research has found that using these devices close to bedtime disturbs sleep:
“When people read the iPad [before bed] they felt less sleepy in the evening, spent less time in rejuvenating REM sleep and their bodies produced less of the sleep-inducing hormone melatonin.
After eight hours sleep, the iPad readers were less alert and felt sleepier.”
The devices seem to disrupt the body’s natural circadian rhythms.
For the new research 14 people either read an iPad or paper book between 9pm and 11pm.
Dr Christian Benedict, study co-author, said:
“Our results could suggest that light exposure during the day, e.g. by means of outdoor activities or light interventions in offices, may help combat sleep disturbances associated with evening blue light stimulation.
Even if not examined in our study, it must however be kept in mind that utilizing electronic devices for the sake of checking your work e-mails or social network accounts before snoozing may lead to sleep disturbances as a result of emotional arousal.”
The other option, of course, is simply to read a real paper-and-ink book in the evening and avoid the luminous electronic devices.
The study was published in the journal Sleep Medicine (Rångtell et al., 2016).
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