Cancer risks associated with a person's body clock and sleep patterns have been reported in previous research and the British…
Cancer risks associated with a person’s body clock and sleep patterns have been reported in previous research and the British researchers wanted to explore more sleep characteristics, as well as some genetic factors that underlie this.
Self-reported morning or evening preferences were registered in more than 180,000 women, led by Dr. Rebecca Richmond, researcher at the Cancer Research UK Integrative Cancer Epidemiology Program and Epidemiology Unit at the University of Bristol, and presented Tuesday at the NCRI Cancer Conference in Glasgow .
Richmond’s team also analyzed genetic variations associated with whether someone is a morning or night person in more than 220,000 women to find out if these can help cause causal relationship to breast cancer.
This type of statistical model, called Mendelian randomization, showed that people whose genes made them more likely to be early stigters were less likely to develop breast cancer by as much as 48%, as evidenced by the 220,000 participants in study.
The second analysis, using self-reported sleep data from 1
80,000 participants, showed a similar trend for early-rising women who had a 40% lower risk of breast cancer. The variation is due to technical differences, Richmond noted.
Women who reported themselves to sleep more than the average seven to eight hours per night also found a slightly increased risk of breast cancer, 20% per extra hour asleep, according to the team’s Mendelian randomization analysis.
But the team points out that many factors are involved in a person who develops breast cancer and that these numbers are not an absolute risk. The finding can not be applied to populations as the majority of women included each of European ancestors.
“Sleep is probably an important risk factor for breast cancer, but it is not as great as other well-established risk factors such as BMI or alcohol,” says Richmond.
About 45% of cancer deaths in the United States are related to alcohol, and breast cancer Now Charity warns that any alcohol intake increases the risk of breast cancer. And obesity will be the leading preventable cause of breast cancer in women in Britain according to a report from earlier this year.
“We know sleep is important in general for health,” said Richmond. “These results have potential political implications for affecting sleep habits in the general public to improve health and reduce risk for breast cancer among women. “
Our circadian rhythms or body watches control body functions like the sweet pattern patterns, blood pressure and metabolism and in the event of disorder may increase the risk of cancer and other diseases.
Richmond’s team conducted its genetic analysis hoping to dig in the possible causes and consequences of this link. But experts warn more research is needed and the existing results can not be applied to a greater extent.
“The statistical method used in this study, called Mendelian randomization does not always allow the causal link to be read, “said Dipender Gill, clinical researcher at Imperial College London. “For example, the genetic determinants of sleep may also affect other neuronal mechanisms that affect the risk of breast cancer regardless of sleep patterns. In such a scenario, sleep patterns may be associated with the risk of breast cancer, but not directly cause it.”
Stephen Burgess, a postdoctor at the University of Cambridge, added that a mechanism for explaining the link is also not known or understood.
“The authors do not show any biological mechanism with which sleep time preferences can affect breast cancer risk. Another limitation is that the sleep chronicle preference (chronotype) is self-reported, and the survey did not specifically recruit individuals with different sleep patterns, such as night shift workers,” wrote Burgess in the study comments.  The study has not yet been published in a medical journal. Gill added that it has not yet been reviewed by other experts in the field.
Read: Sleep: Do you get enough?
Richmond stressed that the 48% lower risk was identified in “extreme” cases where people identified themselves as “determined” morning people from the five categories they could choose from – determined morning, More morning than evening, nor evening than morning, decided evening.
“Sleep is probably an important risk factor for breast cancer,” she said. But it is not as big a risk factor as others well established, such as weight or alcohol consumption, added Richmond.
Nuggets should not be worried about the results, said Richmond. “I would not support women to get up earlier to reduce the risk of breast cancer.”
There are theories about the causes of sleep effect on cancer, she says, as the idea that the artificial light at night leads to hormone interruption.
Dr. Sowmiya Moorthie, senior police analyst in epidemiology at the PHG Foundation, who was not involved in research, added that the study’s great strength is the use of “multiple methods for investigating the connection between sleep pathways and breast cancer, which allows researchers to demonstrate consistency in their findings.”
“As for the impact of research, the existing evidence supports sleep patterns affecting cancer risk, but it is still unclear how individual early or late ascension preferences interact with actual sleep behaviors,” Moorthie wrote in an email.