Why Sleep Matters During Cancer Treatment

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If you struggle with insomnia during chemotherapy, you’re not alone. Sleep issues are one of the most common side effects that people with cancer experience.

Up to half of cancer patients report having sleep problems, according to the National Cancer Institute (NCI).

But while sleep is important for everyone, it’s especially crucial for people with cancer. Poor sleep can put an even greater strain on your body. It can even affect your cancer treatment success and outcomes.

Learn how cancer disrupts sleep patterns — and how getting better sleep improves cancer outcomes.

How Are Cancer and Sleep Linked?

Cancer and sleep are closely intertwined.

Although there’s no proven link, some research suggests that poor sleep can increase your cancer risk. People with cancer often struggle with sleep problems, and poor sleep can lead to worse outcomes.

A major factor is the relationship between sleep and the immune system. Your body’s immune system plays a major role in recognizing and fighting cancer. Sleep boosts your immune system, while poor sleep can affect its ability to do its job.

Poor sleep can also affect your body’s other cells and hormones. This could lead to tumor formation and tumor growth.

The cancer-sleep link may go beyond insufficient sleep. Extended sleep (over nine hours) can also increase your risk of certain cancers.

What Sleep Disorders are Common in Cancer Care?

Up to half of cancer patients report trouble sleeping, the NCI says. That’s higher than the general population. According to the NCI, the two most common sleep disorders in cancer patients are insomnia and circadian rhythm disorders.

Insomnia

Insomnia occurs when you regularly have trouble getting or staying asleep. It can be temporary or long-lasting.

Many different factors can cause insomnia in people with cancer. For example, it can be a side effect of some treatments. Or, you might have trouble sleeping because of cancer-related stress.

According to a 2025 Frontiers in Oncology review, insomnia is most common in the following cancers:

• Breast
• Gastrointestinal (GI)
• Gynecologic
• Lung

But anyone can struggle with insomnia.

Circadian rhythm disorders

Circadian rhythm disorders are problems with your body’s internal clock. Your circadian clock operates on about a 24-hour cycle, helping maintain your sleep-wake cycle and other body processes.

Cancer and cancer treatment can affect your circadian rhythm, disrupting the release of hormones like melatonin and cortisol. Both hormones play key roles in your sleep-wake cycle. A 2024 review in Cancer Medicine reported that those circadian rhythm disruptions could be long-lasting.

Circadian rhythm disorders may also raise your risk of developing cancer. The World Health Organization (WHO) labeled circadian rhythm disorders as a potential carcinogen. Disruptions to your body’s normal cycle can lead to the growth of abnormal (cancerous) cells.

Other sleep disorders

People with cancer may also experience other sleep disorders, including:

• Hypersomnia — Feeling excessively tired and struggling to stay awake during the day. This is different than cancer fatigue, which is a specific complication of cancer and cancer treatment.
• Parasomnia — Unusual behaviors during sleep, such as sleepwalking, talking, or night terrors.
• Sleep apnea — A disorder that causes temporary stoppages in breathing while people are asleep.

People with these sleep disorders may also have a higher risk of developing cancer.

How Does Cancer Affect Your Sleep?

Many factors can cause sleep problems for people with cancer, including:

• Cancer itself — Cancer can cause symptoms throughout your body that disrupt sleep. Tumors may press on nearby organs, causing pain or discomfort. They can affect body systems, such as your GI system or bladder.
• Cancer treatments — Sleep issues are one of many cancer treatment side effects. Chemotherapy, hormone therapy, radiation, and surgery can cause insomnia, other sleep disorders, and side effects that interfere with sleep, like fever or nausea. Medications that manage cancer symptoms can also cause sleep problems.
• Hospital stays — Your cancer treatment may require you to spend time in the hospital. The hospital environment may make it tough to sleep.
• Mental health burdens — A cancer diagnosis can bring on anxiety, depression, stress, and other emotions. These can all make sleep more difficult.
• Other factors — You may have other health conditions not related to cancer that affect your sleep. Lifestyle factors, like a lack of physical activity or sleeping more during the day, can also make it harder to sleep at night.

Can Poor Sleep Impact Cancer Recovery?

Sleep disorders — like insomnia from cancer — can have a significant impact on cancer outcomes.

Poor sleep can:

• Affect your immune system’s ability to fight cancer.
• Increase inflammation, which can cause tumors to grow and spread.

In addition, sleep-related hormone disruption can make cancer more resistant to treatment.

These effects can lead to more advanced cancer and worse results from cancer treatment. It can make you more likely to die from cancer and also increase your risk of cancer recurrence.

Poor sleep can also significantly affect your quality of life. It can make you feel very tired during the day and make cancer side effects worse. It can also affect your mental health, increasing conditions like depression.

How Can I Improve My Sleep During Cancer Treatment?

Many different factors can cause sleeping problems if you have cancer. But it’s important to take steps for better sleep. Improving your sleep can boost your immune system, help with cancer side effects, and improve your quality of life. It may lead to better cancer outcomes.

Try some of these evidence‑based sleep tips for cancer patients.

Talk to your doctor

If you’re struggling with sleep, it’s important to talk to your oncologist. They can help you in several ways.

Your doctor can refer you to a sleep specialist for a polysomnogram (sleep study). This test can help diagnose sleeping disorders and find potential treatments.

Your oncologist can also prescribe medications to help with cancer side effects. This may make it easier to sleep. If a medication you’re taking is causing your sleep problems, they can change your dosage or prescribe a different drug.

Medication

Your oncologist can prescribe medications to help you sleep. This includes drugs to relieve your cancer side effects, along with those that promote sleep. They can also recommend over-the-counter (OTC) medicines and supplements that may help you.

Note: You should always talk to your oncologist before trying any new drug or supplement.

Cognitive behavioral therapy

Cognitive behavioral therapy (CBT) focuses on replacing negative thoughts with positive ones. It can help relieve anxiety and other emotions that are affecting your sleep. Studies have shown that CBT can help with insomnia and other sleep disorders.

Relaxation therapy

Relaxation therapy has become popular for people with cancer. Treatments like acupuncture, massage, and mindfulness meditation may help with pain and other side effects. This can promote better sleep.

Lifestyle changes

Lifestyle changes during the day and at night can also promote better sleep. Here are some of the things you can try:

• Create a comfortable sleeping environment — Keep your bedroom dark, quiet, and at a comfortable temperature. Remove televisions and other electronics from the room. Dress in comfortable clothing and use pillows and blankets for comfort and warmth.
• Eat healthy — Following a healthy diet can support your cancer recovery, but it can also help your sleep. Focus on fruits and vegetables, healthy proteins, and whole grains. Avoid alcohol, caffeine, and heavy meals before bed — they can disrupt sleep.
• Exercise — While exercising may seem difficult during cancer treatment, regular exercise promotes your overall health, including sleep. Talk to your oncologist about ways to incorporate regular exercise into your routine. You should avoid exercising for three hours before bedtime.
• Get outside — Sunlight can help promote melatonin production, which helps with sleep.
• Relax — Try taking a soothing bath, reading a book, or meditating before going to bed.
• Set a sleep routine — Try to go to bed and wake up at the same time, and avoid naps during the day.

UPMC Hillman Cancer Center is the only NCI-designated Comprehensive Cancer Center in western Pennsylvania. We provide comprehensive, compassionate cancer care — including help with sleep problems and other side effects. For information on our services, visit our website.