There may be a correlation between the amount of light in one's room and one's weight, said the Institute of Cancer Research in London. Researchers believe that sleep disruption and circadian rhythms by exposure to light at night (LAN) may be linked to the rise in obesity.
BBC noted that according to the team, "women had larger waistlines if their bedroom was "light enough to see across" at night."
The team examined over 100,000 women and their various bedroom lighting conditions and reported their findings in the American Journal of Epidemiology. Participants rated the amount of light in their bedrooms based on the questionnaire and would indicate if they had light enough to read; light enough to see across the room, but not read; light enough to see your hand in front of you, but not across the room; too dark to see your hand or you wear a mask.
Their responses were then correlated to their physical attributes relating to obesity, including Body Mass Index, waist-to-hip ratio and waist circumference.
The study found that those with more light in their rooms had a tendency to be heavier. There was a significant association between LAN exposure and obesity, wrote the researchers.
Prof Anthony Swerdlow, from the Institute of Cancer Research, told the BBC: "In this very large group of people there is an association between reported light exposure at night and overweight and obesity."
However, scientists cautioned that the the data findings are not entirely conclusive if making one's room less impervious to light would make a difference to your weight. The study is cross-sectional and was not meant to prove causality, only highlight the potential associations between various factors.
"There might be other explanations for the association, but the findings are intriguing enough to warrant further scientific investigation," continued Swerdlow.
Melatonin may be the critical factor in this link between light and the risk of being overweight or obese. Melatonin is the hormone that is inhibited by exposure to light and is associated with one's metabolism. A darkened room is recommended to promote a better and higher quality of sleep.