Sleep and Cancer

There is growing evidence that how well you sleep may be related to the development of certain cancers as well as help you recover and respond to treatment if already diagnosed.

Poor sleep affects hormones that influence cancer cells. Hormones released by the brain such as cortisol and melatonin are affected by the amount of sleep you get. Cortisol is related to stress and typically peaks at dawn, after hours of sleep, and declines throughout the day. It helps regulate the immune system including the release of certain “natural killer” cells that help the body battle cancer.1

Melatonin is involved in the regulation of the body clock and preparing you for sleep. Lack of sleep and melatonin production has been found to be involved in the processes of aging and the development of age-related diseases. A lack of sleep or even light exposure while you are sleeping can affect the amount of melatonin that is released. When levels of melatonin decrease, the body produces more estrogen, which is a known risk factor for breast cancer. This is of particular concern for female night shift workers that are exposed to bright light in the workplace.

sleepy construction worker

Additionally, male night shift workers have been shown to have higher rates of prostate cancer, twice the rate of bowel cancer, and much higher rates of lung and bladder cancer.2 For these reasons, the World Health Organization has classified shift work as a probable cause and risk factor.3

Many patients with cancer also suffer pain or depression, which contributes to difficulty sleeping. These require treatment as in other patients with pain or depression as causes of insomnia. There is much more research that needs to be done on the connections between sleep loss and the development of cancer.

The same advice is given to current cancer patients as well as those who want to lower their risk of developing cancer—make good sleep, nutrition, exercise and stress management a part of your daily routine.

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1National Institutes of Health. National Institutes of Health Sleep Disorders Research Plan.
Last accessed August 5, 2015
http://www.nhlbi.nih.gov/health/prof/sleep/201101011NationalSleepDisordersResearchPlanDHHSPublication11-7820.pdf.
2 Parent MÉ, El-Zein M, Rousseau MC, Pintos J, Siemiatycki J. Night work and the risk of cancer among men. Am J Epidemiol. 2012 Nov 1;176(9):751-9. doi: 10.1093/aje/kws318. Epub 2012 Oct 3.
3 Stevens RG, et al. Considerations of circadian impact for defining ‘shift work’ in cancer studies: IARC Working Group Report. Occup Environ Med. 2011 Feb;68(2):154-62. doi: 10.1136/oem.2009.053512. Epub 2010 Oct 20.