Sleep and Cancer Prevention

By Annapolis Asthma, Pulmonary & Sleep Specialists

Why Rest Is a Critical Part of Long-Term Health

Getting enough sleep is essential to feeling alert and functioning well — but its benefits go far deeper. Quality sleep plays a vital role in supporting the immune system, regulating hormones, and reducing inflammation. In recent years, growing evidence has also shown that poor sleep may increase the risk of certain types of cancer.

One of the key connections between sleep and cancer lies in the body’s circadian rhythm — the internal clock that regulates sleep-wake cycles, hormone production, and cellular repair. When this rhythm is disrupted, either by chronic sleep deprivation or irregular sleep schedules, the body’s natural defense systems may become compromised. For example, night shift work, which exposes people to light at night and alters melatonin production, has been classified as a probable carcinogen by the World Health Organization due to its potential link to breast and other cancers.

Melatonin, the hormone produced in darkness to help induce sleep, also acts as a powerful antioxidant. It helps regulate immune function and may protect cells from DNA damage. Suppressed melatonin levels — which can occur from staying up late or sleeping with artificial light in the room — have been associated with an increased risk of breast and prostate cancers.

Poor sleep also affects immune surveillance, which is the body’s ability to detect and eliminate abnormal cells before they grow uncontrollably. Chronic insomnia, fragmented sleep, or untreated sleep disorders may impair this process, reducing the body’s cancer-fighting capabilities.

In addition, sleep influences inflammation throughout the body. Long-term sleep deprivation can lead to elevated inflammatory markers, which are linked to a higher risk of many chronic conditions — including cancer. Poor sleep is also associated with weight gain and insulin resistance, both of which increase the risk of developing obesity-related cancers, such as colorectal, endometrial, and kidney cancers.

Prioritizing sleep isn’t just about feeling well-rested — it’s a proactive strategy for long-term health. Maintaining a regular sleep schedule, creating a dark and quiet environment, and seeking help for ongoing sleep issues are all steps that support better rest and may reduce the risk of future disease.

While no single factor determines cancer risk, sleep is an often-overlooked contributor that deserves attention — not only during treatment, but also as part of everyday prevention.