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

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

Women who are considered morning people are less likely to develop breast cancer than those who have more energy in the evenings, according to researchers.

The Mendelian randomisation analysis, which included data from BCAC of 122,977 cases of breast cancer and 105,974 women without the disease (the controls), found that a preference for mornings reduced the risk of breast cancer by 40 per cent compared with being an evening type (an "owl"). What's more, every additional hour slept after the recommended eight-hour sleep was associated with a 20 percent increase in risk.

Led by Dr Rebecca Richmond at the University of Bristol, UK, along with the University of Manchester, the University of Exeter, and U.S. and Norwegian researchers, the large-scale study looked at data from taken from 409,166 women to investigate how a person's preference for mornings or evenings as well as their sleep habits may contribute to the development of breast cancer.

But Dr Rebecca Richmond, a University of Bristol researcher who co-authored the study, says it remains unknown how this new finding could influence breast cancer prevention.

Results from 228,951 women enrolled in an global genetic study conducted by the Breast Cancer Association Consortium (BCAC) were also included in the analysis.

The study did not prove a cause-and-effect relationship between sleeping patterns and breast cancer risk.

Now, there's evidence to suggest that the gene mutation may be linked to an increase risk of breast cancer, with night owls more at risk than larks.

"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". "We would like to use genetic data from large populations to further understand how disrupting the body's natural body clock can contribute to breast cancer risk", she said.

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She said policy-makers and employers should take note of the research.

Dan Damon has been speaking to one of the researchers, Professor Richard Martin - an expert in cancer epidemiology from the University of Bristol. Men and women of all ages are encouraged to check themselves for breast cancer as it can affect anyone.

The study was funded by Cancer Research UK and the Medical Research Council. "Another limitation is that sleep timing preference (chronotype) is self-reported, and the investigation did not specifically recruit individuals with different sleep patterns, such as night-shift workers", Burgess wrote in the comments of the study.