(New York Daily) Turn the lights out! Sleeping with a light on has been linked with weight gain in women, according to a new study. Published Monday in the Journal of the American Medical Association, the study analyzed 43,722 women and found that sleeping with an artificial light at night was “significantly associated with increased risk of weight gain and obesity, especially in women who had a light or a television on in the room while sleeping.”
The study found that any kind of artificial light on at night, like a small nightlight, light outside the room and light or television in the room, were associated with weight gain over a six-year period and during a follow-up 12 years after the study began.
Women who slept with a light on in the room or with a television on had a 5 kg, or around 11 pound, or more increase in body weight compared to those who did not sleep with any light on at night. Those who slept with a light in the room or a TV also had a 10% or more increase in BMI, and were more likely to be overweight or obese.
Compared to those who slept with no lights, sleeping with a light or television in the room was linked with a BMI of 25 and 30 — which fall in the overweight and obese range, respectively.
Additionally, women who slept with an artificial light “were less likely to have consistent waking and bedtime patterns and more likely to have less sleep, take a longer time to fall asleep, wake up at night, and take naps. They also used less sleep medication,” the study said.
In addition to an artificial light source, the study noted that light from electronic devices, like smartphones, tablets, computers and e-readers have been associated with poor sleep quality and quantity, excessive daytime sleepiness and being awake longer before being able to fall asleep, the study said.
The study said that evidence from animal studies suggest a number of different functions, including circadian rhythms, melatonin signaling and sleep disruption caused by artificial light during sleep could be cause for weight gain.
“Exposure to ALAN may affect sleep quality, which in turn could affect diet and physical activity,” the study said. These factors were not excluded from the study or adjusted in results, because they could be related factors that contribute to weight gain.
Overall, the study noted sleeping with an artificial light can be generally linked to “a constellation of socioeconomic disadvantage measures and unhealthy lifestyle behaviors, all of which could contribute to weight gain and obesity,” and called for further studies to evaluate the increased risks of weight gain.
Written by: Kassidy Vavra