World Update, 'Morning people' have lower breast cancer risk

BIG DAY OUT Marilyn Rice and Jo Maundrell

BIG DAY OUT Marilyn Rice and Jo Maundrell

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.

The study found that a preference for mornings reduced the risk of breast cancer by 40 per cent compared with being an evening type.

The scientists, led by the University of Bristol, also showed women who slept longer than the recommended seven to eight hours a night increased their chances of a diagnosis by 20 per cent for each extra hour spent asleep.

"We also found some evidence for a causal effect of increased sleep duration and sleep fragmentation on breast cancer, assessed using objective measurements of sleep obtained from movement monitors worn by around 85,000 UK Biobank participants".

"The team used a method called "'Mendelian randomization", which uses genetic variants linked to potential risk factors (in this case, circadian rhythm) to determine whether or not there is a causal relationship between the risk factor and a particular disease (in this case, breast cancer).

'However, the findings of a protective effect of morning preference on breast cancer risk in our study are consistent with previous research highlighting a role for night shift work and exposure to "light-at-night" as risk factors for breast cancer'.

The research was presented at the 2018 NCRI Cancer Conference. And obesity is set to become the leading preventable cause of breast cancer for women in the United Kingdom, according to a report from earlier this year.

"What we can be certain of is that all women - larks and owls - can reduce their risk of breast cancer by exercising regularly, maintaining a healthy weight and reducing their alcohol intake".

And this is involved in breast cancer?

That's according to European researchers looking at International Genetic Data.

But if you are a morning person, feel free to give yourself yet another pat on the back. The World Health Organization already says disruption to people's body clocks because of shift work is probably linked to cancer risk.

The study was funded by Cancer Research UK and the Medical Research Council.

So will a good night's sleep stop me getting cancer?

Dipender Gill, of Imperial College London, said: "Although informative and interesting, this study alone does not warrant any action other than further investigation - people should not be changing their sleep patterns based on the evidence presented here".

"In terms of the implications of the research, it supports existing evidence that sleep patterns influence cancer risk, but it remains unclear how individual preferences for early or late rising interact with actual sleep behaviours", Moorthie wrote in an email.