Artificial light at night may lead to weight gain
Artificial light while you snooze -- such as from a television or bright nightlight – is associated with an increased risk of weight gain and obesity.
This is the main conclusion of a new US study CNN reports. Data were published in JAMA Internal Medicine.
The study involved analyzing 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 – sleeping with a small nightlight or television on, and her body mass index.
Gaining 5 kg for 5 years
Among the women, the researchers found that sleeping with a television or light on in the room over a 5-year period was associated with gaining five kilograms or more, a BMI increase of at least 10%, and a higher risk of being overweight or obese, compared with being exposed to no artificial light during sleep.
In addition, there is a 22% chance of becoming overweight and a 33% chance of becoming obese, explains Dale Sandler, a senior investigator at the National Institute of Environmental Health Sciences in North Carolina and senior author of the study.
No direct cause-effect
But the authors mention you can't point directly to causality between bedroom light exposure at night for a sleeping individual and weight gain but this is definitely a step in that direction, other authors point out.
Further prospective and interventional studies could help elucidate this association and clarify whether lowering exposure to ALAN while sleeping can promote obesity prevention, the authors conclude.