The Benefit of Being an Early Riser: Lower Breast Cancer Risk?

A study found that women who are naturally early risers have a lower risk of developing breast cancer. One in 100 women who were self-professed morning people developed breast cancer compared with two in 100 women who described themselves as evening people. 

The study design included a multivariable regression, one- and two-sample Mendelian randomization and included self-reported preferences for mornings or evenings in more than 180,000 women. The researchers also analyzed genetic variants linked to whether someone is a morning or night person in more than 220,000 women to find out if these could help provide a causal link to breast cancer. 

Investigating causal relationships between sleep traits and risk of breast cancer: a Mendelian randomization study https://t.co/vMrMtTrmp1 #bioRxiv

— bioRxiv (@biorxivpreprint) November 6, 2018

Those who were genetically inclined to more likely be early risers were less likely to develop breast cancer by as much as 48%, according to the findings. The self-reported sleep data showed a similar trend of early risers having a 40% lower risk of breast cancer. 

As the investigators say, is it something about the clock, or do "owls" cause damage thru needing to get up before they want to and consequent shorter sleep?
BBC News – ‘Morning people’ have lower breast cancer risk https://t.co/97GUv9JU3F

— Adrian John Williams (@adrian_ajwsleep) November 6, 2018

Women who self-reported sleeping more than 7 to 8 hours per night had a slightly increased risk of breast cancer of 20% per extra hour slept. 

Good quality sleep can reduce your risk of Breast Cancer by upto 48% https://t.co/VvvCY6mUaZ So why aren’t we spending more resources/time on helping people sleep?

— Dr Rob (GP) (@TeamsforLife) November 6, 2018

“We found consistent evidence for a protective effect of morning preference and suggestive evidence for an adverse effect of sleep duration on breast cancer risk,” the researchers concluded. 

Study observes cognitive decline in older breast cancer survivors.  

Post-menopausal weight loss is linked to reduced breast cancer risk. 

Study finds a higher BMI is associated with a reduced breast cancer risk. 

Sources: CNN & bioRxiv