Does Sleep Affect Cancer Risk?
There’s not enough research to clearly link sleep with cancer risk. However, sleeping well can benefit your health in many ways – physically, mentally, and emotionally. Long-term sleep problems can affect your risk of developing or worsening health problems.
How sleep affects your health
Getting enough sleep and getting quality sleep is important for your overall health. In a normal sleep cycle, there are 2 main stages: REM (rapid eye movement) sleep and non-REM sleep. Quality sleep includes both. Non-REM sleep allows the body to relax and repair itself. REM sleep is deeper and supports brain activity and mental health.
While you are sleeping, your body:
- Uses less energy
- Restores energy
- Repairs itself (if you’re sick or have an injury)
- Produces hormones needed for growth and development
However, many people have trouble sleeping. When sleep is disrupted or not long enough, your brain and body may not be able to function as they should. This can make it harder to do everyday activities.
Experts at the American Academy of Sleep Medicine say getting at least 7 hours of sleep per night is good for adults. Children need more sleep, about 8-12 hours per night, depending on their age, activity level, and growth patterns.
Does sleep affect cancer risk?
It’s unclear. Researchers continue to study how sleep might affect cancer risk. Some studies suggest that the risk of cancer may increase when the body’s sleep cycle is disrupted for long periods of time (chronic sleep problems).
What the research shows
Studies on sleep and cancer risk have unclear results, but here are a few key findings.
Some researchers have proposed that chronic sleep problems may weaken the immune system, which makes it less likely to catch and prevent cancer. On the other hand, quality sleep is known to strengthen the immune system.
Studies show mixed results on short sleep (4-5 hours) and long sleep (more than 9 hours) as an increased risk for cancer.
More research is needed, but a couple of these studies suggest:
- Short sleep may be linked to a higher risk for breast, colorectal, lung, and prostate cancers.
- Long sleep may be linked to higher risk for colorectal and lung cancer.
Shift work may involve varying work hours, switching shifts every few weeks, or working nontraditional shifts, like night shifts. Shift work is common for workers in health care, law enforcement, airlines and travel, factory and mill work, retail stores, and the military.
Research suggests working shifts long-term may be linked to an increased risk of cancer. Shift work may lower the amount of melatonin your body produces. Melatonin is a hormone made by the brain that helps get your body ready for sleep. It also plays an important role in balancing other hormones like cortisol and estrogen. When hormones are not balanced, the risk of cancer might increase.
Experiencing short pauses in your breathing while you sleep might increase cancer risk. Some people don’t know they have sleep apnea. A sleep study can be done to find out if you have it and how serious it might be.
Sleep apnea can be mild (a few pauses of breath) to severe (a lot of pauses of breath). Some studies show that people with moderate or severe sleep apnea might be at an increased risk of cancer. Scientists believe this is because paused breathing during sleep causes less oxygen to be available to the body’s cells. This can cause the body to get stressed and may increase cancer risk.
How to improve your sleep
How you manage your sleep problems depends on their cause. Sleep problems occur for many reasons:
- Lighting changes
- Temperature changes
- Anxiety and stress
- Certain medications
- Physical activity or lack of activity
- Travel
- Physical health issues, such as pain, snoring, breathing problems, heartburn or reflux, hot flashes, and others
- Mental health problems
- Overnight work shifts
- Too little or too much sleep, such as napping during the day
- Alcohol, tobacco, and caffeine use
It’s important to have good habits before bedtime. This is often called sleep hygiene. Your sleep hygiene can improve if you make sure that lighting, noise level, temperature, and location are comfortable before bedtime. Managing sleep problems can also be done through:
- Medications
- Changing habits, such as being more physically active
- Being careful about what you eat and drink in the few hours before going to bed
- Staying active during the day and avoiding napping if possible
- Tracking your sleep to monitor for problems with an app or wearable tracker
- Talking to your health care team about your sleep habits, including what you’ve tracked, to help understand the best ways to manage and improve your sleep
Adding relaxation techniques to your sleep routine can also be helpful. The guided meditation in the video below is a great place to start.
The following video is brought to you by Healing Works Foundation.
A Guided Meditation for Healthful Sleep
Be guided to deeper and longer lasting sleep with visuals and relaxing music. It is best to listen to this meditation when you are in bed.
- Written by
- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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American Academy of Sleep Medicine. Sleep is good medicine. 2023. Accessed at https://sleepisgoodmedicine.com/ on July 23, 2025.
American Society of Clinical Oncology. Sleeping Problems: Hypersomnia, Somnolence Syndrome, and Nightmares. Accessed on cancer.net. Content is no longer available.
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Last Revised: September 2, 2025
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