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(Reuters Health) – A recent study suggests that women who like to wake up early each day are less likely to develop bad cancer than women who prefer to sleep.
Although previous studies have linked an irregular sleep schedule and excessive rest to an increased risk of bad cancer, researchers have not examined the impact of women's waking time on this risk as often, the researchers note. in the BMJ.
For the current badysis, the researchers badyzed the genetic variants badociated with three sleep characteristics: sleep duration, insomnia and a morning or evening chronotype, referring to early birds and to sluggard. They examined data concerning 180,216 women in the Biobank study in the UK and 228,951 women in the Breast Cancer Consortium (BCAC) study.
In the British Biobank study, out of 100 women who got up early, there was one fewer cases of bad cancer than out of 100 women who were late. But there was no clear link between bad cancer and duration of sleep or insomnia.
In the BCAC group, women who woke early also had a lower risk of bad cancer. In this study, sleeping more than the recommended 7 to 8 hours per night was badociated with increased risk – 19% per additional hour.
"The findings of a protective effect of the morning preference on bad cancer risk in our study are consistent with previous research highlighting the role of night work in the development of bad cancer," said Rebecca Richmond, senior author of the study and researcher at the university. from Bristol to the UK
"A particular mechanism that could explain the link, known as the" evening light "hypothesis, involves the suppression of melatonin levels in women exposed to an artificial night light, which influences diverse Hormonal pathways likely to increase the risk of bad cancer, "said Richmond by email.
But women should not rush to reset their awakenings to reduce their risk of bad cancer, Richmond said.
"Our main findings were based on women's stated preferences in the morning or evening, rather than on the fact that they get up earlier or later in the day," Richmond said.
Another disadvantage is that the participants were all of European descent and that the results could be different for women from other racial and ethnic groups.
Most women with bad cancer develop these tumors after the age of 50, and may be more prone to these tumors with family history, certain genetic mutations, dense bad tissue, early puberty or menopause late, according to US Centers for Disease Control. Prevention.
Although women can not control any of these risk factors, there are other lifestyle-related risk factors that can be modified, according to the CDC. These include physical inactivity, overweight, alcohol consumption, first pregnancy after the age of 30, not badfeeding and taking certain hormonal contraceptive pills and of hormone replacement therapy for the symptoms of menopause.
Sleep could also increase the risk, as well as smoking, exposure to certain chemicals and hormonal changes caused by night work, according to the CDC.
The current badysis was not a controlled experiment designed to prove that specific sleep patterns could directly cause bad cancer.
The study does not clearly indicate whether women preferred to get up sooner or later (in accordance with their work hours), said Dr. Eva Schernhammer, author of an accompanying editorial and researcher at the Medical University of Vienna and Harvard Medical School in Boston. Getting up early could make women's waking hours better suited to a typical 9 to 5 hour work day that is common to many jobs.
"The majority of women are neither in the morning nor at night, but fall somewhere between this spectrum, so all potential risks are likely to affect a relatively small proportion of women," Schernhammer said by post electronic. "However, the time of sleep and work could be more important than previously thought."
SOURCE: http://bit.ly/2Y4PIEI BMJ, online June 26, 2019.
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