There is a link between any exposure to artificial light at night while sleeping and weight gain in women.
Women who sleep with a light or television on are 17% more likely to have gained five kilograms or more over five years.
Falling asleep with the TV on or having a bedroom that is illuminated by a street light at night could cause you to gain weight.
Daily exposure to light and darkness helps maintain our 24-hour body clock, which regulates metabolism, sleep-promoting hormones, blood pressure, and other bodily functions.
Although poor sleep by itself was associated with obesity and weight gain, it did not explain the associations between exposure to artificial light while sleeping and weight.
Typical sleep-wake cycle may also contribute to poor health, increasing risks for high blood pressure, diabetes, depression and obesity.
Humans are genetically adapted to a natural environment consisting of sunlight during the day and darkness at night.
Exposure to artificial light at night may alter hormones and other biological processes in ways that raise the risk of health conditions like obesity.