Exposure to light during sleep ‘linked to obesity risk’

A new study has suggested that women who are exposed to greater levels of light while sleeping are more likely to be obese.

Conducted at the Institute of Cancer Research in London with funding from Breakthrough Breast Cancer, the research found that body mass index, waist-hip ratio, waist-height ratio and waist circumference all increased with increasing exposure to light at night.

Cross-sectional analyses of data from the Breakthrough Generations Study, which followed more than 113,000 women from across the UK for 40 years, revealed that these trends persisted independently of factors such as physical activity, having young children and sleep duration.

Although these associations were consistent with previous research examining light exposure and metabolism, the team was unable to determine the sequence of events, or provide evidence of causality.

Study co-leader Anthony Swerdlow, professor of epidemiology at the Institute of Cancer Research in London, said: "We cannot yet tell at this stage what the reason for the associations is, but the results open up an interesting direction for research."

This comes in the same week that a report from The Lancet revealed that young women in the UK are more likely to be obese than any other population in western Europe.