Date
17 December 2017
Blue light emitted by electronic devices prevents the release of melatonin, a hormone that tells our brain it's time to sleep. Photo: Aeon
Blue light emitted by electronic devices prevents the release of melatonin, a hormone that tells our brain it's time to sleep. Photo: Aeon

Blue light from electronic devices disrupts sleep

Are you having problems getting a good night’s sleep? You could blame all the electronic devices in your room.

Recent studies found that the light from computer screens, smartphones and tablets could be affecting the body’s natural sleep cycle. 

In particular, these devices emit blue light, which prevents the release of melatonin, a hormone that tells our brain it’s time to sleep, according to a Washington Post article.

Under normal circumstances, the pineal gland in the brain starts releasing melatonin a couple of hours before regular bedtime. The hormone reduces alertness and induces sleep.

However, light, particularly blue light, can keep the pineal gland from releasing melatonin, thus warding off sleepiness.

Teenagers are more susceptible to this distraction because they are more affected by light than adults.

According to a study by Mariana Figueiro of the Rensselaer Polytechnic Institute in Troy, New York, the blue light emitted by electronic devices is intense enough to affect sleep.

Her research also showed that teenagers are more sensitive to light than adults when it comes to its ability to suppress the release of melatonin. 

Even when exposed to just one-tenth as much light as adults were, the teens suppressed more melatonin than the older ones, the newspaper said.

“The premise to remember is [that] all light after dusk is unnatural,” says sleep researcher Steven Lockley of Harvard Medical School. “All of us push our sleep later than we actually would if we didn’t have electric light.”

A 2013 experiment illustrated this quite dramatically. A group of eight people were made to spend a week camping in the Rocky Mountains, exposed to only natural light and no electronic devices. The effect was that their body clocks were synchronized with the rise and fall of the sun. And regardless of whether they considered themselves as early birds or night owls, all the eight campers reacted in the same way, according to the article.

The effect of light on our body clock has been traced to a special photoreceptor or light sensor in our retina. Called intrinsically photosensitive retinal ganglion cells (ipRGCs), these sensors are unable to pick up on low levels of light, in which case it tells the brain that it is night and time to secrete melatonin. However, ipRGCs are sensitive to blue light, and that is why it is unable to tell the brain that it’s time for the body to sleep.

To counteract the effects of tablets’ blue light on the brain, Figueiro and Lockley recommend a free app, F.lux, that automatically warms up the colors on your various screens — increasing reds and yellows — at sunset and returns them to normal at sunrise.

“The amount of light you need [in order] to see is lower than the amount of light you need to affect your melatonin,” Figueiro said, which means that light-emitting screens can be used at night without disrupting sleep cycles as long as you put some distance between your eyes and the device.

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CG

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