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Light from electronic devices may keep you up at night


Reading is a common activity before bed. A lot of people like to cuddle up with a book or magazine before they turn in for the night. In the 21st century, cell phones and tablets have been added to that list of materials. Though reading is often meant to help us fall asleep, the light emitted from reading devices can actually keep us awake.

This week on “Take Care,” Lois E. Krahn discusses why it is these light emissions make people toss and turn. Krahn is a psychiatrist and sleep expert at the Mayo Clinic in Arizona.

The problem, Krahn says, lies not in the light emitted itself, but in the colors of the visible light wavelengths on the electromagnetic spectrum that are coming from those light emissions. Electronics that people use to read emit blue light, which affects sleep and the brain more than white light does.

“It can be very alerting. So, a blue light that’s directed at the eyes, which happens when you look at it, does turn the brain on in a way that promotes alertness. And at bedtime, you don’t want to be alert,” Krahn says.

Krahn adds that the brain’s pineal gland gets shut down if a person is in a bright room without any eye covering. The pineal gland produces melatonin, a hormone that affects the modulation of sleep patterns.

The best way to avoid losing sleep due to these devices, Krahn says, is simply to avoid them. Otherwise, holding screens further from a person’s eyes or dimming the screen’s brightness is the alternative.

“The absolute safest approach is the old fashioned book or magazine,” Krahn says. “But many people no longer are purchasing those items so they have to figure out how to make the iPad work because they no longer get the newspaper in a paper form. They read it on their iPad.”

Krahn recommends holding an electronic device at least 16 inches away from one’s eyes and to dim the screen’s brightness to 50 percent levels, or at least to a level where content on the screen can still be read.

The effects blue light wavelengths have on the human eyes are nearly immediate. Krahn recommends that if people are going to read or conduct other activities on devices with screens before bed – they should do it early. The earlier they use devices, and the longer the time period between stopping their reading and actually going to sleep, are going to reduce the impact the light has on melatonin and therefore sleep.