However, experts cautioned that other cancer risk factors such as alcohol consumption and overweight have a greater impact than sleep and said there was no reason to change your sleep patterns.
One of 100 women who considered themselves morning people developed breast cancer compared to two in 100 women who described themselves as evening people, according to a study published Wednesday in the BMJ. that sleeping more than the average seven to eight hours per night was found to have a slightly increased risk of breast cancer. It also found there was little link with insomnia.
Researchers used information from over 400,000 women in two large data banks – about 1
"It is important to note that these data do not suggest that modifying sleep habits could eventually lead to a reduction in the risk of breast cancer," Luca Magnani, senior research fellow at the Department of Surgery & Cancer at Imperial College London told the Science Media Center.
"What they suggest is that it appears that the risk of breast cancer is associated with a genetic (thus not modifiable) trait that is in itself associated with a" morning "or" night "preference – what we call 'larks 'and' owls'. "
Dr. Dipender Gill, a Wellcome Trust clinical research fellow at Imperial College London, said the paper is a "useful progress in the field." The study finds that there is a link between sleep-related behaviors and the risk of negative health outcomes, he said in an email to CNN
But the study does not shed light on what causes sleep disorders to affect breast cancer risk. "It may be that certain factors that affect sleep-related behaviors also affect breast cancer risk through a separate mechanism," explained Gill.
In this case, improving sleep patterns would not necessarily reduce the risk of breast cancer, he said. "There is still some way to go before we fully understand the implications of sleeping patterns on health."
Genes, sleep and health
"The message is that perhaps people do not fully appreciate that sleep is really important and has health benefits beyond feeling physically tired and being cognitively alert and so forth," said Relton, who is also the director of the Bristol Population
"The main lifestyle risk factors that we know are clearly associated with breast cancer are alcohol intake and obesity or high body mass index," said Relton
"Sleep is likely to be an important risk factor for breast cancer, but it's not as big as other well-established risk factors like BMI or alcohol, "said lead author Dr. Rebecca Richmond, last year. Richmond is currently a research fellow at the MRC Integrative Epidemiology Unit at the University of Bristol.
It is the people with the greatest mismatch between their chronotype and daily activities that are most at risk, she said.
Schernhammer cited observer studies suggesting that the stresses on our biological clock could be reduced. unlike night owls, early risers that work night shifts have an increased risk of type 2 diabetes. This provided "additional support for the biological importance of circadian misalignment," she said.