Circadian rhythms, otherwise known as your body’s 24 hour sleep/wake cycle, determine when you feel sleepy, and when it’s time to wake up in the morning. Besides your sleep, though, your circadian rhythm can have a number of wide-ranging impacts on your health. According to a new study by researchers at the University of Bristol, breast cancer risk lowers for women who wake up early compared to their night-owl counterparts. While the not-yet-published study still awaits peer review, the findings say that one in 100 women who said that they were morning people developed breast cancer, while two in every one hundred women who described themselves as later risers developed the illness, according to CNN.
CNN reports that, for this study, sleep schedule preferences were reported by over 180 women of European descent in the UK. Cancer risks associated with sleep schedules have been suggested via previous research, and UK researchers set out to expand upon those findings with the current study. While study participants who self-reported as early risers showed lower rates of breast cancer, the reasons for this are still not totally clear, according to the BBC. Lead study author, Dr. Rebecca Richmond, a research fellow in the Cancer Research UK Integrative Cancer Epidemiology Program at the University of Bristol, presented these findings at the NCRI Cancer Conference in Glasgow on Tuesday, according to CNN.
Per the BBC, everyone has a body clock that influences when you sleep, your moods, and maybe even your susceptibility to certain illnesses. Morning people tend to have energy peaks earlier in the day, and get tired earlier in the evening. People who like to go to bed late tend to be most productive later in the evening, and feel sleepier in the morning than early risers do. When circadian rhythms get disrupted, mood and health disorders can result. UK researchers also conducted a genetic analysis of study participants to better understand what the link between sleep patterns and breast cancer risk might be, according to CNN.
“We know that sleep is important generally for health,” Richmond told CNN. “These findings have potential policy implications for influencing sleep habits of the general population in order to improve health and reduce risk of breast cancer among women.”
However, while a link seems to exist between breast cancer risk and sleep patterns, the statistical model used in this study doesn’t necessarily imply causality, Dipender Gill, a clinical research training fellow at Imperial College London told CNN. “For example, the genetic determinants of sleep may also affect other … mechanisms that affect breast cancer risk independently of sleep patterns,” Gill said. So while sleep patterns might be associated with breast cancer risk, they don’t necessarily cause it, according to Gill — there may be other genetic and health factors at play.
“Sleep is likely to be an important risk factor for breast cancer,” Richmond told CNN. But other health factors, like excessive alcohol consumption, are more of a concern, she said. She further stated that night owls shouldn’t worry too much about the study’s findings, as there are many factors, some of which are genetic, that contribute to breast cancer risk.
When it comes to getting enough sleep, and reducing the risk of illnesses like breast cancer, getting to bed earlier when you can might be helpful. And while sleep disruption, or not getting enough solid sleep on a regular basis, can increase your chances for health problems like some cancers, more research is needed to fully understand how circadian rhythm impacts breast cancer risk.