Women who are larks, otherwise known as “morning people”, have a lower risk of developing breast cancer, a study has revealed.
While the exact reason why remains unknown, the team of researchers from the University of Bristol in the UK say their findings are important and add to the growing understanding of how sleep affects our health.
A person’s body clock (also known as their circadian rhythm) regulates when a person feels sleepy or awake over a 24-hour period. So-called morning people wake up earlier, peak earlier in the day and feel sleepy earlier in the evening. In contrast, “evening people” (night owls) get up later, peak later in the day and go to sleep later in the evening.
Using a data analysis technique called Mendelian randomisation, the researchers looked at DNA snippets of more than 400,000 women. They discovered that women who were larks were less likely to have breast cancer than their night owl peers.
Speaking about the findings of the research, Dr Rebecca Richmond, a researcher from the University of Bristol, told the BBC: “The findings are potentially very important because sleep is ubiquitous and easily modified.
“Previous research has looked at the impact of shift work, but this is showing there may be a risk factor for all women.”
Nevertheless, many questions still remain. For example, more research now needs to be conducted to see whether the body clock itself is directly impacting a person’s risk of developing cancer, or if factors like night owls breaking their natural circadian rhythm to accommodate jobs is having an impact.
[Related reading: Major study finds eating processed meat raises risk of breast cancer]