Researchers have found that women who prefer to get up and go to be early have a 40 to 48 per cent lower risk of breast cancer than those whose body clock leads them to feel drowsy in the morning and most energetic in the evening. 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 United States 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.
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.
However, Dr Richmond pointed out that the possible protective effect of being a morning person on breast cancer risk was in keeping with previous research showing that working night shifts and "light-at-night" exposure increased the risk of breast cancer. Experts said the study presented at the NCRI Cancer Conference in Glasgow added to a growing understanding of the importance of sleep in all health. 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.
Cliona Kirwan, consultant breast surgeon and researcher at the University of Manchester, said: "The use of Mendelian randomisation in this study enables the researchers to examine the causal effect on breast cancer of different sleep patterns". These genetic markers can show everything from "chronotype" (what times a person is most active) to risk of insomnia and the amount of sleep needed. Does the body clock affect hormone levels to alter cancer risk, or the immune system, or metabolism?
Out of the 400 000 women, 2,740 were breast cancer survivors and 149 064 were disease free.
"We know already that night shift work is associated with worse mental and physical health".
Careem, one of the region's leading technology organizations, launched a breast cancer awareness campaign in partnership with the Qatar Cancer Society last October.
Read: Sleep: Do you get enough? "This study provides further evidence to suggest disrupted sleep patterns may have a role in cancer development", she said.