16:38 30 May 2014
A team at the Institute of Cancer Research in London says that too much light in a bedroom has a link with obesity levels.
However, they added that there is no enough evidence to instruct people to turn off the lights while sleeping or to buy thicker curtains.
The study, which was published in the American Journal of Epidemiology, was participated by 113,000 women who were asked to rate the amount of light in their bedrooms at night at:
•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
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.
"But there is not sufficient evidence to know if making your room darker would make any difference to your weight.
"There might be other explanations for the association, but the findings are intriguing enough to warrant further scientific investigation."