Study: Higher levels of sleep aid melatonin may reduce prostate cancer risk

SAN DIEGO — Higher levels of melatonin, a hormone involved in the sleep-wake cycle, may decrease the risk of developing advanced prostate cancer, according to results presented here at the AACR-Prostate Cancer Foundation Conference on Advances in Prostate Cancer Research, held Jan. 18-21.

Melatonin is a hormone that is produced exclusively at night in the dark and is an important output of the circadian rhythm, or the body's inherent 24-hour clock. Many biological processes are regulated by the circadian rhythm, including the sleep-wake cycle. Melatonin may play a role in regulating a range of other hormones that influence certain cancers, including breast and prostate cancers.

"Sleep loss and other factors can influence the amount of melatonin secretion or block it altogether, and health problems associated with low melatonin, disrupted sleep and/or disruption of the circadian rhythm are broad, including a potential risk factor for cancer," stated Sarah Markt, doctoral candidate in the Department of Epidemiology at Harvard School of Public Health in Boston. "We found that men who had higher levels of melatonin had a 75% reduced risk for developing advanced prostate cancer compared with men who had lower levels of melatonin," she wrote. "Our results require replication, but support the public health implication of the importance of maintaining a stable light-dark and sleep-wake cycle. Because melatonin levels are potentially modifiable, further studies of melatonin and prostate cancer risk and progression are warranted."

The researchers found that 1-in-7 men reported problems falling asleep, 1-in-5 men reported problems staying asleep, and almost 1-in-3 reported taking sleeping medications.

"Further prospective studies to investigate the interplay between sleep duration, sleep disturbance and melatonin levels on risk for prostate cancer are needed," Markt said.