Researchers continue to study what happens in the sleep-deprived body at a biological level that increases the risk of cancer. They have found that lack of sleep increases inflammation and disrupts normal immune function and both may promote cancer development. In addition, the hormone melatonin, which is produced during sleep, may have antioxidant properties that help prevent cellular damage.
In a study by Patel et a in 2003,researchers reported that women sleeping six or seven hours each night had a lower mortality risk and a reduced chance of dying due to cancer, heart disease, and other causes.
In another study in 2006, Schernhammer et al studied what happens when our sleep cycle is interrupted, as in night shift workers. They studied over 115,022 nurses working the night shift and found an elevated risk of breast cancer after long periods of rotating night work.
In 2008, David E. Blask, demonstrated that night shift workers and others who are regularly exposed to light at night have a higher cancer risk due to suppression of the immune system resulting in a higher risk of breast cancer and other cancers.
In a study published in Cancer in 2010 researchers studied the sleep quality of 1,240 people about to have a colonoscopy. 338 study participants were diagnosed with colorectal cancer. They found that those diagnosed were more likely to average less than six hours of sleep per night and calculated a 50 percent increased risk of colorectal cancer for people sleeping less than six hours per night.
In 2012, Cheryl Thompson, Ph.D., reported that lack of sleep in postmenopausal women was linked to more aggressive breast cancers. One of the researchers said “Short sleep duration is a public health hazard leading not only to obesity, diabetes and heart disease, but also cancer.”
In another 2012 study researchers asked 101 recently diagnosed breast cancer patients about the average amount of sleep they got two years before diagnosis. .They found that the post-menopausal women who slept fewer hours had a higher likelihood of cancer recurrence. The study was the first to suggest more aggressive breast cancers are associated with inadequate sleep.
In 2013, a study published in Cancer Epidemiology, Biomarkers and Prevention reported that men who suffer from insomnia may be at increased risk of prostate cancer. In the study researchers surveyed 2,102 men and followed the 1,347 men in the group who didn’t fall asleep easily and/or experienced disrupted sleep. After about five years, 135 men developed prostate cancer, with 26 of them having an aggressive form of the disease. This represented a two-fold risk of developing prostate cancer if sleep insomnia is present.