Sleeping with light could cause weight gain in women, be it a TV, night light or street light

Women who slept with a light of some kind in their room were more likely to have gained five kilograms (11 pounds) or more during a five-year study

The light may suppress production of melatonin, thereby disrupting circadian rhythm and eating patterns, study authors suggest

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Dozing off to late-night TV or sleeping with other lights on may mix up your body clock and lead to weight gain and even obesity, according to a new study. Photo: AP

Published: 8:30pm, 11 Jun 2019Updated: 8:30pm, 11 Jun 2019

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

The research, which was published in JAMA Internal Medicine, relied on a survey of almost 44,000 US women, with a follow-up five years later.

The women were classified according to their level of exposure to artificial light at night (ALAN) which came from a variety of sources, such as small night lights or clock radios, light shining in from the street, televisions, and room lights.

One of the key findings was that women who slept with a television or a light on in the room were 17 per cent more likely to have gained five kilograms (11 pounds) or more during the study period. The correlation remained strong even after controlling for factors including sleep duration, diet and physical activity.

Light pollution from outside that spills into bedrooms could contribute to weight gain, according to the study. Photo: Bloomberg

Although the authors cautioned they could not definitely draw a causal link, they said their findings added to a growing body of evidence that supports sleeping in a dark room.

“Public health strategies to decrease obesity might consider interventions aimed at reducing ALAN while sleeping,” wrote Dale Sandler and Mark Park Yong-moon of the National Institute of Environmental Health Sciences in North Carolina and co-authors.