Researchers at the University of Bristol presented a study this week at the NCRI Cancer Conference in Glasgow which details the importance of sleep health and the circadian rhythm. The researchers analyzed their data via Mendelian randomization, which “uses genetic variants associated with possible risk factors, such as sleep characteristics, to investigate whether they are involved in causing diseases such as breast cancer.”

The study used data from over 400,000 women in the UK Biobank project and the international Breast Cancer Association Consortium (BCAC). The UK Biobank project previously identified genetic variants that are associated with insomnia, sleep duration, and a person’s preference for being an early bird or a night owl. The researchers found that people who had a preference for being an early bird had a 40 percent reduced risk of breast cancer compared to the night owls. Head researcher Dr. Rebecca Richmond believes further investigation is needed to determine why early risers are less at risk and how “disrupting the body’s natural body clock can contribute to breast cancer risk.”