Study: Bedroom Light Linked to Obesity, Hypertension, Diabetes

Keeping your bedroom dark not only helps you get a good night’s sleep, but can significantly reduce your chances of developing three serious health problems, a new study suggests.

Older men and women who used night lights or left their TV, smartphone or tablet on in the room were more likely to be obese, have high blood pressure, and diabetes than adults who hadn’t been exposed to any. light during the night.

“Maybe even a small amount of light at night isn’t as benign, it can be harmful,” said lead author Dr. Minjee Kim, assistant professor of neurology at Northwestern University Feinberg’s Center for Circadian and Sleep Medicine. Chicago School of Medicine.

He cautioned, however, that the new study does not prove that exposure to light during sleep causes any of these health conditions, only that there may be a link.

And, Kim said, there may be a biological explanation beyond sleep disruption that ties light to an increased risk of obesity, diabetes, and hypertension.

“It’s not natural to see those lights at night,” Kim said. “The light actually turns off some of the parts of the brain that tell our body it’s day versus night. So those signals are messed up in a certain way, because the circadian signal is weakened and, over time, that has implications for the our health. “

So, he said, over time, light can cause metabolic and heart disease.

Kim and her colleagues looked at more than 550 participants in the Chicago Healthy Aging Study. Boys between 63 and 84 wore devices that measured the amount of light in their bedrooms for a week.

Less than half spent five hours in complete darkness while they slept, according to the study. The others were exposed to some light even during the darkest five hours of the day, usually during a night’s sleep.

The researchers said they did not know if obesity, diabetes and high blood pressure prompted people to sleep with a light on or if the light led to the development of the conditions. But, they added, some people with diabetic foot numbness may want to use a night light to help prevent falls when they have to use the bathroom at night.

Emerson Wickwire, a professor and section chief of sleep medicine at the University of Maryland School of Medicine, was not part of the study, but looked at the results. He said the findings add to a growing body of scientific evidence showing the importance of the body’s circadian clock and sleep for overall health, particularly among the elderly.

“What these data show is that exposure to light at night increases the risks for two of the most common and costly chronic medical conditions in the United States and the world – obesity and diabetes – as well as hypertension, a major risk factor. cardiovascular, ”Wickwire said. “While this study deserves close follow-up in future studies, these are exciting results.”

Several factors may explain the worsening health effects of nocturnal light exposure, Wickwire said.

“First, the night light could worsen health by dysregulating the circadian clock,” he said. “In addition to sleep, circadian health is vital for disease prevention and optimal performance.”

Second, Wickwire noted, light is a potent melatonin suppressant.

“Melatonin, also called the hormone of darkness, is associated with multiple health properties, including anti-inflammatory and antioxidant properties. Night light reduces melatonin,” Wickwire said.

In addition to increasing physiological stress, he said, night light can also be an indicator of overall poor health, as people awake at night can be involved in other risky behaviors.

To get the full benefits of sleep, Wickwire has this advice: “Create a sacred sleeping space,” he said. “Your bedroom should be cool, dark, quiet and tidy.”

Kim’s team also has tips on how to minimize bedroom light:

Don’t turn on the lights. If you need to have a light on for safety, do it in a dim light near the floor.

The color of the light is important. Amber or red / orange light is less stimulating for the brain. Do not use white or blue light and keep it away from the bed.

If you can’t control the outside light, use blackout curtains or wear an eye mask.

Position your bed so that the outside light doesn’t shine in your face.

The findings were published June 22 in the journal Sleep.

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