Shorter duration of sleep significantly increased a person’s risk of developing colorectal adenomas in a recent study—a finding that suggests sleep duration as a novel risk factor for colorectal neoplasia.

Although short duration and poor quality of sleep have been linked with heightened risks of obesity, cardiovascular disease, diabetes mellitus, and total mortality, few studies have explored whether these factors affect the development of colorectal cancer. Now, a report in the journal Cancer (2011;117[4]:841-847) reveals that investigators have found a statistically significant association between colorectal cancer and sleep duration.

Principal investigator Li Li, MD, PhD—a professor of family medicine, epidemiology, and biostatistics at Case Western Reserve University School of Medicine—led a team that administered the Pittsburgh Sleep Quality Index  (PSQI) to 1,240 study participants before they underwent a screening colonoscopy. A total of 338 (27.3%) of the enrollees were diagnosed with incident colorectal adenomas, and their PSQI data indicated that they were more likely to average fewer than 6 hours of sleep per night than were control subjects.

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After Dr. Li and colleagues adjusted for various other risk factors of colorectal cancer, people sleeping for less than 6 hours per night were found to have an almost 50% increase in risk of colorectal adenomas compared with those sleeping at least 7 hours per night.

Persons with colorectal cancer also were more likely to report having a diagnosis of sleep apnea and were more likely to have worked alternate shifts, but these differences did not remain significant in all analysis models.

In a separate statement describing these results, Dr. Li noted that the magnitude of the risk observed due to lack of sleep is comparable to the risk associated with having a parent or sibling with colon cancer or having a high intake of red meat. Although the reason for the connection between less sleep and colorectal cancer is unknown, Dr. Li proposed that reduced production of DNA-repairing melatonin or a problem related to insulin resistance could be contributors.

This uncertainty notwithstanding, “Effective intervention to increase duration of sleep and improve quality of sleep could be an underappreciated avenue for prevention of colorectal cancer,” Dr. Li concluded.