Women who are "larks” – morning people who like to rise early, are active earlier in the day and are tired earlier in the evening, have a lower risk of developing breast cancer, a new  UK study finds.

The team at the University of Bristol says the reason why this is so still needs to be uncovered, BBC reports.

The study presented at the NCRI Cancer Conference in Glasgow.

Body clock tells different time

The body clock governs how our organism works in a roughly 24-hour pattern. It's also known as a circadian rhythm. This rhythm affects everything from when we sleep, our mood and even our risk of a heart attack.

Morning people or "larks" are early to rise, peak earlier in the day and are tired earlier in the evening. Evening people or "owls" find it harder to get up in the morning, are productive later into the evening and prefer to go to sleep late.

Body clocks are connected somehow with cancer

Researchers looked at 341 snippets of DNA (the instructions for the human body) that control whether we are likely to be a lark or an owl. They performed an experiment on more than 180,000 women in the UK Biobank project and nearly 230,000 women in the Breast Cancer Association Consortium study.

The comparison demonsttated that people genetically programmed to be "larks" were less likely to have breast cancer than those programmed to be owls.  The study showed  two in 100 owls developed breast cancer compared with one in 100 larks.

Previous research has looked at the impact of shift work, but this is showing there may be a risk factor for all women.", Dr Rebecca Richmond, one of the researchers from the University of Bristol, commented to the BBC.

But she warns that the still need to unpick the relationship between body clock and cancer.

Dr Richard Berks, from Breast Cancer Now, said:

These intriguing results add to the growing body of evidence that there is some overlap between the genetics of when we'd prefer to sleep and our breast cancer risk, but more research is required to unravel the specifics of this relationship."