New research illuminates the dangers of light exposure while sleeping

Jul 02, 2022
The test group were evaluated for CVD risk factors and underwent a 7 day actigraphy recording (a device worn like a wrist-watch that measured sleep cycles, average movement and light exposure for activity and light measures). Source: Getty

Keeping your light while you sleep might not be the brightest idea after a new study discovered the potential risks associated with prolonged night light use.

The Light at night in older age is associated with obesity, diabetes, and hypertension study found that in a sample of older men and women ages 63 to 84 any amount of light while sleeping at night significantly increased the risk of obesity, high blood pressure and diabetes compared to adults who were not exposed to any light during the night.

Northwestern University Feinberg School of Medicine Assistant Professor of Neurology and the study’s corresponding author, Dr. Minjee Kim said “older adults already are at higher risk for diabetes and cardiovascular disease, so we wanted to see if there was a difference in frequencies of these diseases related to light exposure at night.”

“Whether it be from one’s smartphone, leaving a TV on overnight or light pollution in a big city, we live among an abundant number of artificial sources of light that are available 24 hours of a day,” Kim said.

The 552 participants who took part in the study underwent a detailed examination of blood pressure, weight, height, cholesterol, glucose and other known risk factors for heart disease. In addition, they wore an actigraphy device on their non-dominant wrists for seven days and filled out a daily sleep diary. Over half of the actigraphy devices used were able to measure light, which constituted the basis of this new study.

Researchers were surprised to discover that less than half of the study participants consistently had a five-hour period of complete darkness per day. The rest of the participants were exposed to some light even during their darkest five-hour periods of the day, which were usually in the middle of their sleep at night.

Although the findings pointed to an association between exposure to light while sleeping and an increased risk of developing of diabetes, diabetes and hypertension, researchers were unable to determine whether these conditions cause people to people to sleep with the light on or if the exposure to the light contributed to the development of the conditions.

Chief of sleep medicine at Feinberg and a Northwestern Medicine physician and co-senior author of the study, Dr. Phyllis Zee stressed that despite the perceived uncertainty,“it’s important for people to avoid or minimize the amount of light exposure during sleep”.

Researchers are considering further studies to test whether restoring the natural light-dark cycle can improve health outcomes.

IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.

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