Many children are afraid of the dark, but there are also adults who still prefer to keep a light on in their bedroom throughout the night. If you are one of them, be careful, because there is scientific evidence that warns that sleeping with artificial lighting can harm your health. A few years ago, a study by the Institute of Health Sciences and the Environment in the United States linked exposure to artificial light at night while sleeping with weight gain in women, and this same year another study revealed that ambient light in the bedroom can damage the heart and increase insulin resistance.
Now, new research from Northwestern University in Chicago has found that older men and women who used nightlights or left the TV, smartphone or tablet on in the bedroom while they slept were more likely to be obese. and having high blood pressure and diabetes, compared with adults who had not been exposed to any lighting at night.
“Perhaps even a small amount of light at night can be harmful,” said Dr. Minjee Kim, an assistant professor of neurology at the Center for Sleep and Circadian Medicine at Northwestern University Feinberg School of Medicine. and lead author of the paper, who cautioned that the new study, however, does not prove that light exposure during sleep causes any of these health conditions, but rather that there may be a link, and that there may be a biological explanation beyond sleep disruption, which associates light with increased risk of obesity, diabetes, and hypertension.
“It’s not natural to see those lights at night,” he said. “The light actually turns off some of the parts of the brain that tell our bodies that it’s day or night. So those signals get mixed up in a way, because the circadian signal gets weaker, and over time that has implications for our health” and can lead to metabolic and heart disease.
Why light interferes with sleep and harms health
Kim and her colleagues studied more than 550 people ages 63 to 84 who participated in the Chicago Healthy Aging Study and used devices that measured the amount of light in their bedrooms for a week. They found that less than half spent five hours in complete darkness while sleeping, and that the others were exposed to some light, even during the darkest five hours of the day, usually in the midst of their nightly sleep.
“Melatonin is associated with multiple health properties, including anti-inflammatory and antioxidant properties, and light at night reduces melatonin.”
The researchers acknowledge that they don’t know if obesity, diabetes, and high blood pressure cause people to need to sleep with a light on, or if it’s the light that leads to these health problems, since some people with numbness in diabetic feet may want to use a night light to prevent falls when getting up to go to the bathroom at night.
Emerson Wickwire, professor and section chief of sleep medicine at the University of Maryland School of Medicine, who was not involved in this study but has reviewed its results, points to several factors that may explain the worsening effects on sleep. health from light exposure at night.
According to him, first of all “light at night could worsen health by deregulating the circadian clock”, and “in addition to sleep, circadian health is vital for disease prevention and optimal performance”. Second, he continues, light is a powerful melatonin suppressant. “Melatonin, also called the hormone of darkness, is associated with multiple health properties, including anti-inflammatory and antioxidant properties. Light at night reduces melatonin.
To reap the full benefits of a good night’s sleep, Wickwire recommends: “Create a sacred space to sleep.” “Your bedroom environment should be cool, dark, calm, and uncluttered.” The researchers have also offered some tips for keeping the light in the bedroom as dim as possible:
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