Tip/Thought of the Day

Light Exposure During Sleep Causes Variety of Health Issues

Previously, we’d shared how light exposure during sleep can result in weight gain. Sleep hygiene refers to the habits that one can maintain to help promote better sleep. Everything from going to sleep at the same time every night, turning off screens a couple of hours before sleep, and making sure that you sleep between 7-9 hours of sleep are all important factors in whether your body actually benefits from the sleep you get. New studies now show that one factor of sleep hygiene- whether you sleep in darkness- can significantly impact your overall health.

Exposure to even moderate ambient lighting during nighttime sleep, compared to sleeping in a dimly lit room, harms your cardiovascular function during sleep and increases your insulin resistance the following morning, reports a new Northwestern Medicine study.

“The results from this study demonstrate that just a single night of exposure to moderate room lighting during sleep can impair glucose and cardiovascular regulation,” said senior study author Dr. Phyllis Zee, chief of sleep medicine at Northwestern University Feinberg School of Medicine and a Northwestern Medicine physician. “It’s important for people to avoid or minimize the amount of light exposure during sleep.”

Insulin resistance is when cells in your muscles, fat and liver don’t respond well to insulin and can’t use glucose from your blood for energy. To make up for it, your pancreas makes more insulin and over time, your blood sugar goes up. Eventually, this can lead to increased risk of diabetes, heart disease, and metabolic syndrome, in addition to causing damage to your nerves, blood vessels, and organs. How can light during sleeping cause such a cascade of events within our bodies?

Previous studies have shown that light impacts the body during the day by increasing our heart rates and activating the sympathetic nervous system as needed. The sympathetic nervous system is primarily responsible for enabling the body’s fight or flight reactions, but also maintains balance of physical and chemical functions. When the body utilizes the sympathetic nervous system, it produces catecholamines (hormones made by the adrenal glands), as well as other hormones like cortisol. But, when those substances are constantly produced, it results in physiological consequences such as hypertension (high blood pressure), increased risk of cardiovascular disease, and hyperglycemia (high blood sugar).

This new study found that the body reacts similarly when exposed to light at night. “In addition to sleep, nutrition and exercise, light exposure during the daytime is an important factor for health, but during the night we show that even modest intensity of light can impair measures of heart and endocrine health,” said co-first author Dr. Ivy Mason, who at the time of the study was post-doctoral fellow at Northwestern and now is a research fellow at Harvard Medical School.

Sleep is essential for the body to function. During sleep, the brain forms and maintains pathways that promote learning and memory, as well as help concentration. Recent research also shows that as your body rests, toxins that build up over the course of the day are removed from your brain. Sleep restores our energy and relaxes our muscles. During sleep, cells are restored throughout the body, and hormones and essential protein levels adjust to support essential functions. From head to toe, our body requires sleep to rest, heal, and thrive. Turning the lights down is another facet of healthy sleep habits that support our body’s functions.

Try these tips to get you started:

  • Maintain sleep regularity- go to sleep at the same time each day
  • Sleep at least 7-9 hours, daily. Evidence shows, however, that too much sleep can impact your health too.
  • Avoid bright lights in the time before sleep, as it cues your body’s circadian rhythm to stay awake and active. Wear an eye mask or get blackout curtains if your sleep space isn’t dark.
  • Tune out loud noises using white noise or ear plugs to promote calm.
  • Develop a relaxing routine that helps your body recognize that sleep time is near. Try washing up, setting out your clothes for the next day, stretch, turn on calming music, etc. to shift into relaxation mode.

Read our post on sleep hygiene for more tips on how to promote better sleep- your body will thank you for it!



-https://news.northwestern.edu/stories/2022/03/close-the-blinds-during-sleep-to-protect-your-health/

-https://en.wikipedia.org/wiki/Sympathetic_nervous_system

-https://www.webmd.com/diabetes/guide/diabetes-hyperglycemia

-https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep

-https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-science-of-sleep-understanding-what-happens-when-you-sleep

-https://www.nichd.nih.gov/health/topics/sleep/conditioninfo/what-happens

-https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep

-https://my.clevelandclinic.org/health/articles/11443-blood-sugar-hidden-causes-of-high-blood-sugar-levels-in-the-morning

-https://www.physio-pedia.com/Sympathetic_Nervous_System

-https://medlineplus.gov/lab-tests/catecholamine-tests/

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