by Mike Cohen, Director, Center for Brain Training
Do whatever you can to keep your bedroom as dark as possible when sleeping.
Turn off the TV. Put away your mobile or tablet. Dial the lights way down.
The reason may not be what you think.
A 2022 study published in the journal PNAS* concluded that a dark room has big benefits for better sleep quality and overall health, whereas a lighter room can be detrimental.
Reason One: Snoozing in a room with artificial light as dim as a 25-watt bulb can increase insulin resistance. (Insulin resistance occurs when your body doesn’t respond as it should to insulin, negatively impacting blood sugar.)
Reason Two: Sleeping in a lighted room prevents your heart from slowing at night like it’s supposed to because the light triggers the body to go into a higher state of alertness. A heart rate that doesn’t slow down sufficiently keeps your body from resting properly.
The potential “side effects” of sleeping in a lighted room have been identified as risk factors for heart disease, diabetes, and metabolic syndrome, notes senior study author Dr. Phyllis Zee, Chief of Sleep Medicine at Northwestern University Feinberg School of Medicine.
According to a news release from sciencedaily.com, 20 adults participated in the study in which 10 were randomly selected to sleep in a lighted room and the other 10 in a dimly lit environment.
Investigators found that insulin resistance occurred the morning after people slept in a lighted room at a higher level than those who slept in a dark room.
They also found that those sleeping in a lighted room had a higher heart rate than they should have, diminishing the quality of rest.
The sciencedaily.com article explained that exposure to artificial light at night during sleep is common, either from indoor light-emitting devices or sources outside the home. Outside sources are a particular problem in brightly lit urban areas. They reported that up to 40 percent of people sleep with a bedside lamp or other light in the bedroom, or keep the television on.
Dr. Zee cautioned that if you’re able to see objects clearly in the bedroom, you probably have too much light in the room.
Here are some of her tips for reducing light during sleep:
(1) If you must have a light in your room, make it a dim light, and keep it closer to the floor.
(2) The color of light is important. Avoid white or blue light. Amber or a red/orange light is less stimulating for the brain. (Note from Mike Cohen: Common sources of blue and white light include screens like smartphones and TVs as well as LED and LCD lights. Consider acquiring eyeglasses designed to filter out this light from screens.)
(3) Use blackout shades or an eye mask if you can’t control the light. Move your bed so the outdoor light isn’t shining on your face.
Light isn’t the only factor that affects sleep quality.
Your environment can have a HUGE impact on sleep. For example, WiFi, mobile phones, and screen time at night can diminish sleep quality. Other factors include eating at the wrong time, eating foods that impede blood sugar regulation, and inadequate exercise.