WEDNESDAY, May 8, 2013 — Most everyone knows regular sleep is essential to good health. For some time, scientists have explored how poor sleep quality or lack of shuteye, may increase one’s risk for developing several diseases, especially cancer.
Until recently, such research has focused primarily on the impact poor sleep quality has on women’s cancer risk. One study, published last May, found working night shifts can increase a woman’s risk for developing breast cancer by as much as 40 percent. Another study from March linked late night work shifts to a 24 percent higher risk for advance-stage ovarian cancer and as much as a 49 percent higher risk for early-stage ovarian cancer.
However, researchers now are finding that men who don’t get their Zzzs may also be at high risk for developing cancer. A new study, just published in Cancer Epidemiology, Biomarkers & Prevention, found an association between sleep problems — such as difficulty falling asleep and staying asleep or waking too early — and prostate cancer risk. In the study, researchers observed that men with sleep problems had up to a two-fold higher risk for developing prostate cancer, compared with those who didn't have sleep problems.
“The men who reported having a sleep problem were overall at increased risk of prostate cancer but the associations were even stronger for advanced disease,” said Lara Sigurdardottir, MD, a professor at the Centre for Public Health Sciences at the University of Iceland and lead author of the study.
Dr. Sigurdardottir and her team of researchers followed data from the Age, Gene/Environmental Susceptibility-Reykjavik study (AGES-Reykjavik), which included a population-based cohort of 2,425 men ages 67 to 96. Study subjects were instructed to answer a four question survey about their sleeping habits: whether or not they took sleeping aids, had trouble falling asleep, woke in the middle of the night with difficulty sleeping again, or woke early in the morning and were unable to fall back to sleep. Almost 9 percent of the subjects reported they have severe sleep problems, while 6 percent said they had very severe sleep problems.
Working night shifts, sleeping during the day, or simply failing to get undisrupted and restful shuteye, can disturb a person's natural circadian rhythm and halt the production of melatonin, the hormone that's essential to the human sleep-wake cycle. In daylight hours, light stimulates the nerve pathway from the retina to hypothalamus, the part of the brain that helps the body’s nervous system communicate with the endocrine system via the pituitary gland. The hypothalamus regulates a number of the body’s functions, including internal temperature, natural steroid production, and stress regulation.
“The presence of melatonin has been shown to inhibit or slow down tumor growth in experimental studies, including prostate cancer,” said Sigurdardottir, who added that related studies have also verified this. “Suppression of melatonin such as with light exposure or pinealectomy increases tumor growth in experimental studies.”
A number of factors can precipitate sleep problems. They may include circadian rhythm disorders, insomnia, narcolepsy, periodic limb movement disorder, restless legs syndrome, some psychiatric disorders, and sleep apnea. Men, in particular, often suffer from sleep apnea, a disorder characterized by abnormal breathing and heavy snoring, which weakens overall sleep quality.
Nathaniel F. Watson, MD, MSc, associate professor of neurology at the University of Washington and co-director of the university’s Sleep Center, said unfortunately the root cause of poor sleep is difficult to identify and diagnose because a person won’t experience the symptoms of their disorder while they’re awake, “unless they have a bed partner or witness to describe to them what’s happening."
Watson said poor sleep habits often go hand-in-hand with other lifestyle choices that overall don’t encourage good health, such as smoking and eating an unhealthy diet.
To improve sleep quality, Sigurdardottir recommends patients make several lifestyle adjustments. They include avoiding caffeine, alcohol, and nicotine intake, and especially six hours before heading off to bed. She said it can also be helpful to engage in activities that you find relaxing before going to sleep such as a hot bath or shower, breathing and meditation, and reading a good book.
Additionally, Watson recommends people keep their pets out of the bedrooms and avoid napping during the day. “Napping can reduce the drive to sleep,” he said. He cautions against working in bed and urges people to use their bedroom only for sleeping and sexual activity.
Sigurdardottir said it's also best to avoid direct light, especially from televisions and computer screens and tablets. Removing the television from your bedroom may help to curb the temptation. “Similarly, if you have to wake up during the night, try to avoid turning on a bright light,” she added.
Last Updated: 5/3/2013