A Harvard study has revealed that frequent ejaculation may significantly reduce the risk of developing prostate cancer—a disease that affects one in eight men and is the second-leading cause of cancer death among men in the U.S.

The 2016 study, published in European Urology, tracked 31,925 men over nearly two decades. Researchers found that men who ejaculated at least 21 times per month had a 20% lower risk of developing prostate cancer compared to those who did so less frequently.

“Higher ejaculation frequency in adulthood was associated with lower prostate cancer risk,” the study noted, especially for low-risk disease.

Prostate cancer is most common in men over 65, with increased risk among African American and Caribbean men of African ancestry.

Beyond cancer prevention, masturbation may also improve sleep. German health provider Barmer Krankenkasse and sex therapist Judith Golden suggest that the endorphin release from orgasm helps with relaxation and falling asleep—making it a natural remedy for insomnia.