Circadian rhythm, 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. Apart from your sleep, your circadian rhythm can have a number of broad effects on your health. According to a new study by researchers at the University of Bristol, the risk of breast cancer is lower for women who wake up earlier than their owl counterparts. While unpublished studies are still awaiting peer review, findings say that one in 100 women who say they are morning people develop breast cancer, while two out of every hundred women who describe themselves as people who wake up then develop disease, according to CNN.
CNN reports that, for this study, preference for sleep schedules was reported by more than 180 women of European descent in England. The cancer risk associated with sleep schedules has been suggested through previous research, and British researchers set out to expand these findings with current research. While self-reported study participants as people who wake up early show lower rates of breast cancer, the reason for this is still not entirely clear, according to the BBC. The main study author, Dr. Rebecca Richmond, a researcher in the UK Cancer Integrative Epidemiology Research Program at the University of Bristol, presented these findings at the NCRI Cancer Conference in Glasgow on Tuesday, according to CNN.
According to the BBC, everyone has a body clock that affects when you sleep, your mood, and maybe even your vulnerability to certain diseases. Morning people tend to have peak energy in the morning, and get tired early in the night. People who like to sleep late tend to be most productive at night, and feel more sleepy in the morning than getting up early. When the circadian rhythm is disrupted, mood disorders and health can occur. British researchers also conducted a genetic analysis of study participants to better understand what the relationship between sleep patterns and breast cancer risk might be, according to CNN.
"We know that sleep is important in general for health," Richmond told CNN. "These findings have potential policy implications for influencing general public sleep habits in order to improve health and reduce the risk of breast cancer among women."
However, while the relationship seems to exist between breast cancer risk and sleep patterns, the statistical model used in this study does not necessarily imply a causal relationship, Dipender Gill, a clinical research training fellow at Imperial College London told CNN. "For example, sleep genetic determinants can also influence other mechanisms … which affect breast cancer risk independently of sleep patterns," Gill said. So when the sleep pattern is possible related with the risk of breast cancer, they don't need to cause it, according to Gill – there may be other genetic and health factors that play a role.
"Sleep tends to be an important risk factor for breast cancer," Richmond told CNN. But other health factors, such as excessive alcohol consumption, are more concerning, he said. He further stated that night owls should not worry too much about the research findings, because there are many factors, some of which are genetic, which contribute to the risk of breast cancer.
When it comes to getting enough sleep, and reducing the risk of diseases like breast cancer, sleep early when you might be able to help. And while sleeping disturbance, or not getting enough sleep regularly, can increase your chances of health problems such as some cancers, further research is needed to fully understand how circadian rhythms affect the risk of breast cancer.