Although exercise has generally been found to prevent cancer, combining it with poor sleep may be a risk factor.
Among 4,033 women younger than 65 who had at least 20 hours of physical activity per week, those who slept less than seven hours nightly had a 47% higher risk of developing cancer (95% CI 5% to 105%) within the next 10 years, reported James J. McClain, Ph.D., of the National Cancer Institute.
- Poor sleep in other women was not a cancer risk factor and high exercise showed a protective effect against cancer in the entire sample.
- The study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until they have been published in a peer-reviewed journal.