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Bright Lights Before Bed Disrupt Sleep in Children, Says New Study

Bright Lights Before Bed Disrupt Sleep in Children, Says New Study

A lot of parents rely on the iPad to help their child decompress before bed. But you might want to reconsider this nightly habit. A new study[1] found that evening exposure to bright electric light lowered melatonin production in preschoolers, making it more difficult for them to nod off and stay asleep. Melatonin is the hormone responsible for regulating circadian rhythm, the 24-hour internal clock that manages sleep and wake cycles. A recent feature by Salon draws on the new study and explores the connection between melatonin suppression and longer term health problems, including cancer.

Melatonin levels drop within 10 minutes of bright light exposure

The 2018 study was conducted by the Sleep and Development Laboratory at the University of Colorado. Ten children, ages 3 to 5, were exposed to a 1000 lux (the unit of luminescence) light therapy box — the equivalent of approximately 90 candles — for one hour before their usual 8pm bedtime. The children stopped producing melatonin within just 10 minutes of light exposure and this continued for another hour after the lights went out.

Smartphone use before bedtime could be just as risky

The study looked at how fluorescent lights can influence melatonin levels. But the researchers note that the light emitted from electronics like smartphones could produce similar results. Specifically, blue light, a short wavelength of light found in digital screens (TVs, computers, laptops, smartphones, and tablets), electronic devices, as well as fluorescent and LED lighting is the subject of concern.

Previous studies have shown that the blue light from electronics can disrupt sleep in adults[2]. Since you typically hold these devices close to your face, the authors surmise that “young children are more sensitive to the effects of light emitted from these sources.”

“The almost ubiquitous nature of electronic media use in this young age group supports the critical need for studies assessing the effect of evening electronic media use on melatonin levels, circadian timing, and subsequent sleep and alertness early childhood,” wrote the researchers.

Salon also pointed to a previous study that found dimmer lights didn’t lower melatonin levels to the same degree as bright lights — in fact, dimmer lights lowered melatonin by 9 percent, compared to bright lights that lowered melatonin nearly entirely.

Related: Nighttime Light Exposure Causes Depression, Says Study

Poor sleep quality linked to cancer

The Salon article explored the possible long-term effects of poor sleep quality in children. The disruption of circadian rhythms has been linked to cancer in adults[3] and children[4]. Leukemia the most common cancer in children[5]— is caused by an uninhibited growth of white cells, which are generated by stem cells. Studies show that stem cell proliferation is under circadian control, so essentially too much light at night destabilizes stem cell growth, suggesting a possible link to cancer[6].

Four simple steps to limit your children’s exposure to nighttime light

There are steps you can take to limit your child’s exposure to light at bedtime:

  1. Eliminate all smartphone use after dinner: Help your child find other ways to slow down and decompress at the end of the day. Bring out drawing materials, puzzles, or books after dinner. Focus on family time and doing activities together that help everyone wind down ahead of bedtime.
  2. Have your child sleep in a pitch-black room: Make sure their room is as dark as possible – block all possible light sources from the doors, windows, and any remaining interior lights. Use fabric or curtains on windows or consider buying blackout curtains. Cover all light switches and alarm clocks with black electrical tape or True Dark Dots, which are stickers you can put over light switches and clocks. You can also use a towel to block light from coming in from under the door.

If you’re worried about the effects of a nightlight on your child’s sleep, there are two steps you can take to ensure the light they are exposed to is the best possible solution.

  1. Dim the lights in your child’s bedroom: Downgrade the light wattage… For instance, if you have 100 watt light bulbs in their bedroom, downgrade to 75 watts. Keep going until you are down to a tiny night light.
  2. Purchase the best nightlight for the job: While blue light is the most harmful light to be exposed to at night (yes, that’s what in your phone or tablets), studies show that red light doesn’t affect melatonin to the same degree[7]. So consider a red LED nightlight. You can buy a red light that doesn’t impact melatonin at all, or if that’s too creepy, try an amber light, which barely affects it.

Bonus: Buy your children red-colored glasses to wear after dinner and until bedtime. In this Bulletproof Radio podcast episode, Dave reveals that he wears red-colored glasses in the evening hours to get ready for sleep. Listen to the podcast for more do’s and don’ts of light hacking.

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