A team at the University of Bristol in England analyzed data from 180,215 women enrolled with the UK Biobank project, and 228,951 women who had been part of a genome-wide association study of breast cancer led by the international Breast Cancer Association Consortium. The findings, which were not peer-reviewed, were presented at the NCRI Cancer Conference in Glasgow, Scotland.
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Using a genetic method known as Mendelian randomization, researchers found that women who prefer mornings have a 40 to 48 percent reduced risk of developing breast cancer. Also, the research notes that women who slept longer than seven to eight hours had a 20 percent increased risk per additional hour slept.
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Rebecca Richmond, a research fellow at the University of Bristol involved in the study, said the findings could have implications for those working night shifts. Still more studies must be done to understand the connection between waking up earlier or later in the day and breast cancer diagnosis.
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"It may not be the case that changing your habits changes your risk of breast cancer; it may be more complex than that," Richmond said in a statement.
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