Sleeping This Much Could Increase Your Risk of Cancer

Getting the perfect amount of sleep every night could keep your risk for cancer at bay.

Female feet under blanket flat lay. Female beautiful feet with red pedicure on the bed. Top view on the sleeping woman legs under gray blanketGolubovy/Shutterstock

You may know that sleeping too much—or too little—can harm your health in numerous ways. Weight gain, heart disease, diabetes, and mental health issues like depression have all been linked to poor slumber. Now it looks like poor sleeping habits could raise your risk of breast cancer, according to a study by researchers from the University of Bristol in England.

The British researchers turned to two large genetic data banks to arrive at their research; believe it or not, there are genetic markers for insomnia, oversleeping, and whether you’re likely to be an early bird or a night owl. Because the data banks also had medical records, the researchers were able to compare sleep tendencies and breast cancer cases in more than 400,000 women, all told.

The results? Women who love mornings—the researchers referred to them as “larks”—were half as likely to develop breast cancer compared to women who stayed up late. The study also suggests that a woman’s risk for the disease increased by 20 percent for every additional hour she slept beyond the recommended eight hours. Don’t miss the secrets to better sleep that doctors want you to know.

“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,” Dr. Rebecca Richmond, the study author, said in a press release. “These findings have potential policy implications for influencing sleep habits of the general population in order to improve health and reduce risk of breast cancer among women.” Next, read up on 10 more surprising things that can raise your cancer risk.

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Ashley Lewis
Ashley Lewis received her Master’s Degree from CUNY Graduate School of Journalism in 2015. She was a Jason Sheftell Fellow at the New York Daily News. and interned at Seventeen and FOX News before joining Reader’s Digest as an assistant editor. When Ashley is not diligently fact-checking the magazine or writing for, she enjoys cooking (butternut squash pizza is her signature dish), binge-watching teen rom-coms on Netflix that she’s way too old for, and hiking (and falling down) mountains.