Women who sleep with the television or a light on in the bedroom may be more likely to gain weight, a new study has claimed.

The research conducted a survey of almost 44,000 US women, with a follow-up five years later. The women in the study were classified according to their level of exposure to artificial light at night (ALAN) which came from a variety of sources, from small nightlights or clock radios to light shining in from the street to televisions or room lights.

One of the key findings was that women who slept with a television or a light on in the room were 17 percent more likely to have gained five kilograms (11 pounds) or more during the study period.


Authors suggested that the light may be suppressing the production of melatonin, thereby disruption circadian rhythm and eating patterns.

Other possibilities were that light acts as a “chronic stressor” disrupting the release of stress hormones such as glucocorticoids that play a part in regulating food intake, or that there may be another mechanism at work that affects metabolism directly.

The authors acknowledged several limitations including that the data was self-reported and they did not know how intense various light sources were.

High light exposure may also “reflect a constellation of measures of socioeconomic disadvantage and unhealthy lifestyle behaviours, all of which could contribute to weight gain and obesity.”

A professor of Chronobiology at the University of Surrey in Britain agreed with the finding saying, “To maintain good sleep hygiene, avoid light and electronic distractions in the bedroom.”