A recent study has linked an increased risk of weight gain and obesity to keeping the lights switched on while sleeping.
In the study published in the journal, JAMA Internal Medicine, the scientists wrote that sleeping with the television or the lights in the bedroom switched on was positively associated with gaining five kilogrammes, or 11 pounds, over a five-year period among women.
A senior author, Dr Dale Sandler, said, “There was a 17 per cent chance of gaining five kilogrammes after we adjusted for confounding factors. In addition, there was a 22 per cent chance of becoming overweight and a 33 per cent chance of becoming obese.
“We are in the middle of an obesity epidemic in the United States and the things that we usually think about obesity prevention are hard for people to do – eat a better diet, get more exercise – and we don’t seem to be making a dent. If this study’s findings are true and if they can be replicated, then it is a very easy public health message to turn off the lights when you’re sleeping.”
The researchers’ analysed data on 43,722 women aged 35 to 74, in the United States.
The data came from a nationwide cohort study called the Sister Study that enrolled women between 2003 and 2009. The data included information on each woman’s sleeping habits, such as if she slept with a small nightlight or television on, and her body mass index.
The women’s self-reported sleeping habits were divided into four categories: no light, small nightlight in the room, light outside of the room, and light or television in the room.
Women who reported more than one type of artificial light were categorised at the highest level of exposure. Women who slept with a mask on or reported no light while sleeping were classified as experiencing no artificial light exposure.
The researchers took a close look at each woman’s sleeping habits and her weight and obesity risk over a five-year period.
Among the women, the researchers found that sleeping with the television set or light switched on in the room was associated with gaining five kilogrammes or more, a BMI increase of at least 10 per cent and a higher risk of being overweight or obese, compared with being exposed to no artificial light during sleep.
