Women who naturally get up early have a lower risk of developing breast cancer than do evening types in new studies. One in 100 grandparents had breast cancer.
Cancer risk associated with human body clocks and sleep patterns has been reported in previous studies, and UK researchers wanted to investigate further sleep characteristics and found genetic factors for them.
Self-reported preference for morning or evening time was recorded according to their definition of their preference. Cancer Research More than 180,000 women led by Rebecca Richmond, a researcher at the UK Integrated Cancer Epidemiology Program and the Department of Epidemiology at Bristol University, presented at the NCRI Cancer Conference in Glasgow on Tuesday.
The Richmond team also analyzed the genetic variants associated with whether someone was a person in the morning or at night. Find out if more than 220,000 women can identify causal relationships with breast cancer.
This type of statistical model, called Mendelian randomization, is used by people who are likely to find genes that are less likely to cause breast cancer As seen in the 220,000 study participants, it increased to 48%.
The second analysis showed similar trends of early women with a 40% lower risk of breast cancer using data reported by 180,000 participants. The difference is due to technical differences, Richmond said.
Women who have slept for an average of 7 to 8 hours per person have also increased their chance of getting breast cancer by 20 percent.
However, the researchers point out that there are many factors involved in breast cancer, and these figures are not absolute risks. Also, because the majority of women involved are European ancestors, the results of the study can not be applied to the population as a whole.
"Sleep may be an important risk factor for breast cancer, but it is not as large as other well-established risk factors such as BMI or alcohol.
According to the American Cancer Society, 45 percent of cancer deaths in the United States are related to modifiable risk factors such as tobacco smoke, overweight, modified meat and meat intake. About 4 percent of US cancer deaths are related to alcohol, and breast cancer charity warns that alcohol consumption increases the risk of breast cancer. Obesity will also be a major cause of breast cancer prevention in British women, the report said earlier this year.
"We know sleep is generally important for health," Richmond said. "This discovery has potential policy implications that could affect the sleeping habits of the general population to improve women's health and reduce breast cancer risk," he said.
Our diurnal rhythm or body clock regulates body functions such as sleep patterns, blood pressure and metabolism, and if interrupted it can increase the risk of cancer and other diseases.
The Richmond team conducted a genetic analysis to explore possible causes and effects of this link. However, experts warned that more research is needed and that existing studies can not be applied more widely.
"The statistical method used in this study, called Mendelian randomization, is not always analogous to causality," says Dipender Gill, director of clinical research at Imperial College London. For example, genetic determinants of sleep can affect other connective mechanisms that affect breast cancer risk, independent of sleep patterns. In these scenarios, sleep patterns can be associated with the risk of breast cancer, but not directly. "
Stephen Burgess, a postdoctoral fellow at Cambridge University, said the mechanism describing the link was neither known nor understood.
"The author does not show the biological mechanism that sleep timing preference can influence breast cancer risk. Another limitation is self-reported sleep timing preference (chronotype) I did not adopt it, "Burgess wrote in the study.
This study has not yet been published in the medical journal. Gill added that he has not yet received peer reviews by other experts in the field.
Reading: Sleep: Is it enough?
Not as large as other factors.
Richmond found that 48 percent of people in the five categories identified themselves as "certain" among "clear morning", "more morning than evening", "evening before morning", "evening before evening" .
"Sleep is likely to be an important risk factor for breast cancer," she said. But according to Richmond, it is not as large as other well-established risk factors such as weight or alcohol consumption.
The night owl does not have to worry about the results, Richmond said. "I will not advocate that women should get up early to reduce the risk of breast cancer."
There is a theory about sleep causes for cancer. It is the idea that artificial light causes hormone destruction at night.
Dr. Sowmiya Moorthie, senior policy analyst at PHG Foundation Epidemiology, who has not participated in this study, added that the main strength of the study is "to use different approaches to investigate the association between sleep traits and breast cancer." They showed consistency in their discovery. "
"Although the findings support existing evidence that cancer risk is associated with cancer risk, it is unclear how individual preferences for early or late increases interact with actual sleep behavior," Moorthie told E-mail.