According to an article by Adam Marcus, dated October 15, 2010, in Reuters Health Information, in one recent study, "people who slept less than six hours a night were more likely to have dangerous polyps in their colon or rectum compared to better-rested patients."
Approximately 10% of these polyps develop into cancerous tumors. But don't be mistaken...the findings don't prove that lack of sleep causes these polyps to occur, only that lack of sleep could be one factor in colon cancer.
The study doesn't show how these two criteria might be connected. However, Dr. Li Li at Case Comprehensive Cancer Center wonders if the sleep hormone melatonin protects against cancer tumors.
At any rate, researchers have much to ponder.