Sleeping with Even a Little Light at Night Can Be Unhealthy, study finds

Young beautiful blonde woman lying in bed suffering from alarm clock sound covering head and ears with pillow making unpleasant face. Early wake up, not getting enough sleep, going work concept

All those little gadgets we have in our rooms putting off light may be negatively impacting our health. New research suggests that sleeping with even just a little light on may impact cardiovascular and metabolic health.

What impact does light in your sleeping environment have on your health?

Doctors wanted to find out what kind of impact the presence of light in our sleeping environment had on our health.

As electronics have crept more and more into our lifestyle, we are surrounded by them in our sleeping environment. Even when we aren’t using them, many have status LEDs that put off a significant amount of light. That alone is such a problem that LED light-blocking stickers have become a product category in itself.

Beyond that, some people sleep with the TV on or have nightlights.

The question the doctors wanted to answer was: Should we be doing this? Does this light have an effect on us or not?

When the doctor’s research was completed, they were surprised to find that even a little light is harmful.

Sleeping with any light on could be harmful to your health, study finds

The study was conducted by Dr. Phyllis Zee, director of the Center for Circadian and Sleep Medicine at Northwestern University, and her team of researchers there, NPR reports.

The study was small, involving 20 subjects. In addition, the team also analyzed data from 552 people, ages 63 to 84, who had participated in the Chicago Healthy Aging Study, MBG Health reports.

The team designed tests that would measure the physiological effects of 100 lux of artificial light on healthy adults while they were sleeping.

How bright is 100 lux light?

“This is about enough light that you could maybe see your way around,” says Dr. Zee, “but it’s not enough light to really read comfortably.”

The test started by having all the participants sleep in darkness the first night, then the next night, exposing half of the subjects to the light.

The researchers tested the brain waves and measured the heart rates of the sleepers, as well as through their blood every few hours assessing glucose and melatonin levels, among other procedures. In the morning, the participants were given a large dose of sugar to see how well their metabolic systems responded to the glucose spike.

Results of light in sleeping environment

The results were published in the Proceedings of the National Academy of Sciences in June. The work of the researchers showed that even a small amount of light in the sleeping environment can have negative effects on both cardiovascular and metabolic health, particularly for older people. The sleepers who were exposed to light had elevated heart rates throughout the night. There were effects on their metabolism, such as increased insulin resistance the next morning.

Dr. Zee and her team believed this small amount of light was enough to activate the sympathetic arm of the autonomic nervous system — which is responsible for the body’s fight or flight response. They believe the small amount of life was enough to trigger the nervous system to remain in a more active and alert state.

“It’s almost like the brain and the heart knew that the lights were on, although the individual was sleeping,” Dr. Zee said.

A wealth of research has already shown that interruptions to circadian rhythms make it harder for the body to regulate blood glucose levels.

The research suggests that the effect the presence of even a low light can have on sleep, such as increased insulin resistance, will increase the risk of chronic diseases such as further insulin resistance, diabetes, and other cardiometabolic problems.

The takeaway

The study showed a clear connection between being exposed to even low levels of light during sleep and cardiometabolic function. Although further research is needed, the results of this study indicate that, for better health, sleep in a cool, quiet, and dark environment.

Especially if you are 55 or older, this research appears to indicate the effect of light on metabolic and cardiovascular health, which in turn, can lead to or worsen chronic disease.

Finally, consider ways to block out light such as turning off the TV, removing nightlights, placing stickers over LED status lights (that can block or dim light), and/or removing certain electronics from your sleeping environment.