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Sleepless Bedfellows: Insomnia, Cancer, and Circadian Disruption

Insomnia is the most common sleep disturbance in those with cancer. It affects between one-half and three-quarters of those diagnosed. Up to 40 percent of cancer survivors continue to suffer from sleep problems.1-3

However, the problem of sleeplessness runs deeper than worries about cancer. The immune system, so important for battling cancer, needs adequate sleep to help your body manage related hormone imbalances and therapy side effects.

Without sleep, you risk losing your body’s best chance to fight cancer and heal its damage. Then, not only does cancer thrive, but its symptoms — daytime fatigue, increased pain sensitivity, and mood disruption — could worsen.

Why does cancer wreak such havoc on sleep?

Why people with cancer have insomnia


If, before diagnosis, you experienced insomnia (or circadian dysfunction, see below), it’s likely to return, magnified, both during illness and following successful treatment.


Living with cancer naturally creates anxiety. What does the future hold? Will treatment work? What about relapses? The uncertainty and overwhelm, and feeling you’ve lost control of your own body, can cause insomnia.

Related to this is orthosomnia, or the stress of losing sleep over sleep loss. Try to remember: some nights may be rough, but resting — even without sleep — is still better than stress.4


Cancer disrupts sleep when it causes:

  • Anemia
  • Hot flashes
  • Inflammation
  • Pain


Drugs to fight cancer, relieve pain, manage side effects, or treat other conditions can cause daytime fatigue, insomnia, or both.


Radiation and chemotherapy can cause insomnia through circadian disruption.

Circadian rhythm's link to fighting cancer

The human circadian system exists to manage balances in bodily functions. Healthy circadian rhythms rely on consistent periods of sleep and alertness shaped by the light-dark and seasonal cycles of the planet.

At night, as natural light dims, the body releases natural melatonin (the “sleep hormone”) to transition us to sleep. In the morning, when the sun rises, our melatonin production stops so we can awaken and start the day.

These rhythms promote the growth, metabolism, division, and genetic repair of healthy cells. This is precisely why circadian rhythm disorders make fighting cancer a challenge.

What happens when circadian rhythms fail?

Circadian rhythm disorders occur as glitches in the circadian system. They give cancer opportunities to take root and spread.

People who can’t help going to bed far too early or too late exhibit circadian dysfunction. So do people who work the night shift and people with blindness. Another form of temporarily disrupted circadian rhythms: jet lag. As many as half of cancer patients experience long-range circadian disruption.5

Daytime fatigue may be to blame. It can lead to frequent naps which may disrupt circadian rhythms. When nighttime comes, the body isn’t ready for sleep again, leading to sleep-onset insomnia.

Fortunately, the use of melatonin supplements supports the body’s ability to fight cancer, reduce chemo side effects, and minimize drops in blood cell counts while undergoing radiation.Research suggests that management of circadian rhythmicity lies at the heart of future improvements to cancer treatment.6,7

Pathways to better sleep for those with cancer

Sleep hygiene

Try these first to make sure you’ve done your due diligence.

  • Go to bed at the same time every night.
  • Rise at the same time every day.
  • Put away screens at least one hour before bedtime.
  • Expose yourself to sunlight first thing in the morning.
  • Get regular exercise in the morning for a daily circadian “reset.”
  • Avoid caffeine, alcohol, and heavy meals at bedtime.
  • Practice bedtime relaxation (warm baths, soft music, stretching, breathing, meditating, massage).
  • Create a supportive sleep environment that’s dark, cool, quiet, and with few distractions.

Cognitive behavioral therapy for insomnia

Some cancer centers offer cognitive behavioral therapy for insomnia (CBT-i). This specialized behavioral approach supports your ability to fall and stay asleep. CBT-i remains the gold standard treatment for insomnia, helping many reclaim the sleep they’ve needed to get through bouts with cancer.8


This useful supplement assists chronotherapy in conjunction with cancer treatment to support circadian health. However, the timing and dosage of melatonin make a difference; ask your oncologist for melatonin dosage and scheduling for best results.

Sleeping pills

While many of these come with risks, drugs that induce sleep may succeed in cases of stubborn insomnia that resist other forms of treatment.


This describes the specific timing of cancer treatment. Many oncologists now tailor treatments to match the unique circadian rhythms of their patients in order to improve effectiveness and tolerance. Ask your doctor if chronotherapy could help you.5

Sleep to prevent cancer’s spread

Getting adequate, uninterrupted sleep can defend against metastasis by:9-12

  • Bolstering the immune system
  • Improving daytime function
  • Elevating mood
  • Halting its spread

Do you also have cancer, or another chronic illness, that causes a "Sleepless Bedfellow" with your insomnia? Tell us about how you manage getting adequate, uninterrupted sleep to help defend your immune system too.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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