Women who like having a lie-in in the morning are more likely to develop breast cancer than early risers, a new study suggests.
Researchers who studied the sleeping habits and genetic data of almost 410,000 women found that “larks”, who function best in the morning, were 40% less likely to develop breast cancer than “night owls”, who feel more alert in the evening.
The study, by a team at the University of Bristol, showed that over an eight-year period, “two in 100 owls developed breast cancer, compared with one in 100 larks”, reports the BBC.
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Women who slept for more than the recommended seven to eight hours per night were also found to have a 20% increased risk of the deadly disease per additional hour in bed, says The Times.
Lead scientist Dr Rebecca Richmond said the researchers had looked at genetic variants associated with people’s preference for morning or evening, sleep duration and insomnia, to investigate the possible link between the natural body clock and the disease.
Around one in seven women in the UK will develop breast cancer in their lifetime.
Experts hope the new findings, presented at the NCRI Cancer Conference in Glasgow, may help women cut their risk. But, according to Richmond, it’s not that simple.
“We would like to do further work to investigate the mechanisms underpinning these results, as the estimates obtained are based on questions related to morning or evening preference, rather than actually whether people get up earlier or later in the day,” she said.
“In other words, it may not be the case that changing your habits changes your risk of breast cancer - it may be more complex than that.”
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