The Surprising Reason Leaving the Lights on at Night Spikes Your Diabetes Risk

Falling asleep by the light of a lamp or the glow of a screen can hurt your health.

Although people can reduce their risk of developing diabetes through their lifestyle choices, the World Health Organization (WHO) reports that the number of people with the condition worldwide rose from 108 million in 1980 to a staggering 442 million in 2014.

In an International Journal of Health Sciences article, Syed Amin Tabish, MD warned that "Diabetes is a major public health problem that is approaching epidemic proportions globally," noting that "​​the most dramatic increases in Type 2 diabetes have occurred in populations where there have been rapid and major changes in lifestyle, demonstrating the important role played by lifestyle factors and the potential for reversing the global epidemic."

Some of the ways you can decrease your risk of diabetes might surprise you—including one common, seemingly benign nighttime habit. Read on to find out more.

READ THIS NEXT: If You Notice This in the Bathroom, It Could Be the First Sign of Diabetes.

Most people with diabetes have Type 2.

Women giving herself a blood sugar test.

The term "diabetes" refers to a chronic condition that involves your body's process of turning food into energy, explains the Centers for Disease Control and Prevention (CDC). However, Type 1, Type 2, and gestational diabetes (diabetes during pregnancy) are all distinct types of this condition.

The exact cause of Type 1 diabetes is not known—although genetics, environmental factors, and even certain types of viruses can cause the disease, explains the Mayo Clinic.

Approximately 90-95 percent of people with diabetes have Type 2, reports the CDC. "With Type 2 diabetes, your body doesn't use insulin well and can't keep blood sugar at normal levels," they say, noting that "Type 2 diabetes can be prevented or delayed with healthy lifestyle changes." The CDC explains that while gestational diabetes occurs during pregnancy and usually goes away after birth, it can spike the risk of developing Type 2 diabetes later on.

Prediabetes offers the opportunity for prevention.

Doctor talking with patient in an office.

An estimated 96 million adults in the US have a condition called prediabetes, according to the CDC. However, they estimate that 80 percent of people with prediabetes are unaware that they have it, because it can have mild symptoms or no symptoms at all for a long period of time.

"Prediabetes is a serious health condition where blood sugar levels are higher than normal, but not high enough yet to be diagnosed as type 2 diabetes," they explain. "Prediabetes puts you at increased risk of developing type 2 diabetes, heart disease, and stroke."

The potential causes of prediabetes vary. In addition to gestational diabetes, other contributing factors include being overweight, physical inactivity, and an unhealthy diet. "The good news is that prediabetes and Type 2 diabetes are largely preventable," advises the Harvard Public School of Health. "About nine in ten cases in the U.S. can be avoided by making lifestyle changes."

Some surprising factors can contribute to the risk of diabetes.

Couple walking on an outdoor path.

The Harvard Public School of Health explains that preventing Type 2 diabetes "can be boiled down to five words: stay lean and stay active." This advice refers to the fact that eating a healthy diet and engaging in regular physical exercise can be effective ways of reducing your risk of the disease. Researchers have found, for example, that taking a walk after eating a meal and consuming certain foods, like fatty fish and whole grains, can lower your risk of Type 2 diabetes.

However, preventative measures extend to many other aspects of your life—some of them surprising. Researchers have found connections to aspects of emotional wellness such as feeling lonely and the risk of Type 2 diabetes. And a new study published in the journal Diabetologia found that leaving the lights on when you go to sleep at night can actually increase your risk, as well.

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Leaving a light on at night can have unintended effects.

Woman sleeping in bed with a light on.

Many people keep a light on at night even after they've fallen asleep. For some, it's an oversight, like leaving the television on, but others keep the lights burning to prevent nighttime falls or simply to provide an added feeling of safety.

While a connection between Type 2 diabetes and this seemingly harmless habit might seem far-fetched, a study found that "chronic exposure to light pollution at night raised blood glucose levels and led to a higher risk of insulin resistance and diabetes," CNN reported. In fact, researchers found that "Sleeping for only one night with a dim light, such as a TV set with the sound off, raised the blood sugar and heart rate" of a group of twenty-something test subjects.

This is significant because "An elevated heart rate at night has been shown in prior studies to be a risk factor for future heart disease and early death, while higher blood sugar levels are a sign of insulin resistance, which can ultimately lead to type 2 Diabetes," said CNN.

While Phyllis Zee, MD told CNN that people should limit their exposure to light at nighttime—her suggestions included utilizing light-blocking window shades and a sleep mask—she also emphasized the importance of being out and about in natural light. "Get light during the day," she told the site. "Daylight is healthy!"

Luisa Colón
Luisa Colón is a writer, editor, and consultant based in New York City. Her work has appeared in The New York Times, USA Today, Latina, and many more. Read more
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