Published: Thu, June 13, 2019
Medicine | By Brett Sutton

Bedroom light at night might cause women weight gain

Bedroom light at night might cause women weight gain

While the study doesn't prove that sleeping with a light on causes weight gain, it suggests the two may be linked, the researchers said.

He added: "These new findings won't change the advice to maintain good sleep hygiene, and avoid light and electronic distractions in the bedroom, but they add further strength to the case for this advice".

Bottom Line: Exposure to artificial light at night, especially sleeping with a light or television on in the room, was associated with increased risk of weight gain and overweight and obesity among a large group of women studied.

The National Institutes of Health study published today isn't proof, but it bolsters evidence suggesting that too much exposure to light at night could pose health risks.

The study, by the National Institute of Environmental Health Sciences, North Carolina, only studied women aged 35-74, with no history of cancer or cardiovascular disease, and also made sure they didn't work shifts, sleep in the day and weren't pregnant when it started.

The data on artificial light exposure during sleep and weight gain were self-reported, and the women were not asked why they kept lights on while sleeping.

The researchers analyzed health and lifestyle data on almost 44,000 US women enrolled in an ongoing study seeking clues to causes of breast cancer.


A BMI between 18.5 and 24.9 is considered healthy, while 25 to 29.9 is overweight, 30 or above is obese and 40 or higher is severely or morbidly obese.

The television and any bedside or overhead lights need to go off, and then people need to look for other light sources to eliminate, he advised.

"Unhealthy high-calorie diet and sedentary behaviors have been the most commonly cited factors to explain the continuing rise in obesity", Dr. Park said. Many - about 17,000 - slept with a nightlight in the room, while more than 13,000 left a light on outside the bedroom and about 5,000 slept with a television or light on in the bedroom. While a fatty eating routine and inactive way of life are the most regularly referred to clarifications for stoutness, some past research has likewise connected exposure to counterfeit light during the evening to an expanded danger of weight gain, analysts note in the study.

Artificial light exposure at night from things like streetlights, storefronts, and even cell phone use, for example, can disrupt the natural light-dark cycle of circadian rhythms and suppress the release of the sleep hormone melatonin.

Professor Malcolm von Schantz, from the University of Surrey, commented on the study, saying: 'The findings make flawless biological sense.

'We know from experimental studies in people that light at night affects our metabolism in ways that are consistent with increased risk of metabolic syndrome.

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