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.
"Using genetic variants associated with people's preference for morning or evening, sleep duration and insomnia, which had previously been identified by three recent UK Biobank genome-wide association studies, we investigated whether these sleep traits have a causal contribution to the risk of developing breast cancer", she said.
"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", she noted.
It said in a statement that the breast cancer awareness week was observed around the world in the month of October, as an annual worldwide campaign organised by major breast cancer charities to increase awareness of the disease and to raise funds for research into its cause, prevention, diagnosis, treatment and cure.
"These are interesting findings that provide further evidence of how our body clock and our natural sleep preference is implicated in the onset of breast cancer", said breast surgeon Cliona Kirwan.
Researchers then mapped the genetic variations between the earlier risers and the night owls and compared it with that to the risk of developing cancer.
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More research will be needed to look into the relationship between sleep patterns and breast cancer, so don't have a massive panic if you're a late to bed, late to rise type of person just yet.
The study used a genetic method known as Mendelian randomization.
AXA Mansard, a member of AXA, a global leader in insurance and asset management, said it joined in the observance of the concluded breast cancer awareness.
"We know already that night shift work is associated with worse mental and physical health".
"The authors do not show any biological mechanism by which sleep timing preference could influence breast cancer risk".
Dan Damon has been speaking to one of the researchers, Professor Richard Martin - an expert in cancer epidemiology from the University of Bristol. "I wouldn't support that women should get up earlier to reduce risk of breast cancer". "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.