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One Two Zzzzz
Want a good night's sleep and to feel healthy these holidays? Then don't do this
Backlit e-readers are not a good thing when you’re trying to have a restful night, researchers say.
PICKING UP A good book on an e-reader before bed might feed your brain – but it’s probably damaging your health.
Researchers from the Harvard Medical School have found that using a light-emitting e-book or iPad to read before bed made it harder for people to sleep and lowered the quality of the shut-eye they did get when snoozing.
It also delayed the body’s natural circadian clock – the process which sets people’s systems according to a 24-hour rhythm – with knock-on effects for general health and alertness when awake.
Earlier research had shown that blue light, the powerful, short-wavelength kind electronic devices put out, had an impact on the body’s rhythms, but less was known about what it did to sleep.
In the 2-week study, 12 patients read e-books on iPads for 4 hours before bed each night for a week – then repeated the process with printed works.
Those using the digital devices took longer to sleep, were more awake in the evening and spent less time in restorative REM sleep stages.
They also had lower levels of the hormone melatonin, which naturally helps people feel sleepy in the evenings.
The iPad uses were more aware at night however they were less alert the following morning, even after getting a full 8 hours of sleep.
E-readers, laptops and cellphones all out
While the study used the Apple tablets, researchers said they also tested the theory with other blue-light emitting devices like backlit e-readers, laptops and cellphones.
E-books without built-in lights, like the original Kindle, did not produce the same negative sleep effects.
Sleep expert Prof. Frank Baldino said there had been a general drop in average sleep length and quality over the past 50 years.
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,” he said.
Chronically low levels of melatonin from night-time exposure to light has been linked to increased risks of several diseases, including breast and prostate cancers.
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