Being a ‘morning person’ cuts the risk of breast cancer, research suggests.
A major study examining the genes of 400,000 women found a significant difference in the chances of developing breast cancer between morning people and those who prefer evenings.
The researchers, led by the University of Bristol, believe women who prefer to stay up at night are more likely to have a disturbed body clock. They are also exposed to a greater level of artificial light at night, which has been shown to increase breast cancer risk because it affects women’s hormones.
The scientists, writing in the British Medical Journal, stressed the risk was small but significant. For every 100 women who prefer mornings, one fewer would get breast cancer than every 100 who prefer evenings, they found. This pales in comparison with other factors that increase breast cancer risk, such as drinking and obesity. But with the 54,000 new cases of breast cancer diagnosed in the UK every year – and 11,000 deaths – avoiding even this small increase in risk could make a major difference.