PNAS: Keep your blinds closed while you sleep to protect your health

Close the blinds, draw the curtains, and turn off all the lights before going to bed

"The results of this study suggest that just one night of exposure to moderate indoor lighting during sleep impairs glucose and cardiovascular regulation, which are risk factors for heart disease, diabetes, and metabolic syndrome

There is already evidence that daytime light increases heart rate by activating the sympathetic nervous system, which makes your heart beat faster and increases your alertness for the challenges of the day

"Our findings suggest that exposure to light during nighttime sleep has a similar effect," Zee said

The research will be published March 14 in the Proceedings of the National Academy of Sciences

In a well-lit room, the heart rate increases and the body does not get proper rest

"We found that when you sleep in a well-lit room, your heart rate increases," said Daniela Grimaldi, PhD, a research assistant professor of neurology at Northwestern University and one of the study's first authors

The sympathetic and parasympathetic nervous systems regulate our physiology during the day and night

How lights at night can lead to diabetes and obesity

The researchers found that people developed insulin resistance the morning after sleeping in a well-lit room

A study published earlier in JAMA Internal Medicine looked at a large group of healthy people who were exposed to light during sleep

"Now we're showing a mechanism that might be the underlying reason why this happens," Zee said

Participants in the study were unaware of the physiological changes in their bodies at night

"But the brain perceives it," Grimaldi said

Exposure to artificial light while sleeping at night is common

Exposure to artificial light during nighttime sleep is common, either from indoor lighting fixtures or from sources outside the home, especially in large urban areas

Light and its relationship to health is a double-edged sword

"In addition to sleep, nutrition and exercise, light during the day is an important factor for health, but at night, we found that even moderate levels of light impair measures of cardiac and endocrine health," Zee said

The study tested the effect of participants sleeping overnight at 100 lux (moderate light) and 3 lux (dim light)

"These findings are very important, especially for those living in a modern society where nighttime light is increasingly common, both indoors and outdoors," Zee said
.

Advice on reducing light during sleep

(1) Do not turn on the lights
.
If you need a light on (seniors may need one for safety), turn the light on a little closer to the floor
.

(2) Color is very important
.
Amber or red/orange light is less stimulating to the brain
.
Do not use white or blue light and keep it away from sleepers
.

(3) If you can't control the outdoor light, a sunshade or eye mask is a good choice
.
Move your bed so that outside light doesn't hit your face
.

Is my room too bright?

"If you can see something well, it's probably because it's too bright," Zee said
.

Other Northwestern authors are co-first author Ivy Mason, a postdoctoral fellow at Northwestern during the study period and now a fellow at Harvard Medical School, Kathryn Reed, Chloe Warlick, Ronnie R.
Dr.
Mulkani and Dr.
Sabra Albert
.

Magazine

Proceedings of the National Academy of Sciences

method research

observational study

research topic

people

Article publication date

14-March-2022