Early risers less likely to develop breast cancer, new study reveals

WOMEN WHO are “larks” and at their best early in the morning are less likely to develop breast cancer than their night-owl sisters, a study has found.

Scientists who discovered the association also unearthed evidence of a causal link between sleeping longer and the disease.

The researchers who compared data on hundreds of thousands of women found that those with an in-built morning preference were 40 per cent to 48 per cent less at risk of breast cancer.

Part of the analysis also showed that women who slept longer than the recommended seven to eight hours per night increased their chances of being diagnosed by 20 per cent per additional hour spent asleep. The study highlighted individuals who were genetically predisposed to be either “larks” or “owls”.

Larks tend to get up and go to bed early, while owls have a body clock that leads them to feel drowsy in the morning and most energetic in the evening.

Lead scientist Dr Rebecca Richmond, from the University of Bristol, said: “Using genetic variants associated with people’s preference for morning or evening, sleep duration and insomnia ... we investigated whether these sleep traits have a causal contribution to the risk of developing breast cancer.

“We would like to do further work to investigate the mechanisms underpinning these results, as the estimates obtained are based on questions related to morning or evening preference rather than actually whether people get up earlier or later in the day.

“In other words, it may not be the case that changing your habits changes your risk of breast cancer; it may be more complex than that”