About Breast Cancer>Side effects > Insomnia and fatigue

Insomnia and fatigue


Cancer-related insomnia and fatigue are very common with a breast cancer diagnosis and treatment, and can develop for many reasons. Insomnia is difficulty falling and staying asleep. Cancer-related fatigue is significant tiredness, exhaustion, and weakness that is not relieved after sleeping. Insomnia and fatigue can be caused by emotional stress, treatment, or the cancer itself.

Lack of sleep and fatigue can make you feel so tired that you have trouble getting through the day. They can affect your self-esteem, emotions, relationships, and work. We know how overwhelming it can be, and we're here for you. On this page, we'll walk you through the specific symptoms and causes of breast cancer-related insomnia and fatigue. We'll also share tips for talking with your care team about insomnia and fatigue, and links to information about managing these side effects.


What are the symptoms of cancer-related fatigue?

You know what it’s like to be physically exhausted after a tough week at work, a busy day of hiking, or chasing a toddler. Fatigue related to cancer or its treatments is different. It’s a constant feeling of tiredness or complete exhaustion that is unrelated to your recent activity. Even a good night’s sleep doesn’t help.

Symptoms of cancer-related fatigue include:

  • Feeling tired, even after a night’s rest
  • Lacking energy or having less energy
  • Difficulty concentrating
  • Lack of motivation
  • Increased irritability, anxiety, or nervousness

Cancer-related fatigue can:

  • Last for long periods and take away your energy to do even easy everyday tasks
  • Make you feel tired, weak, and sluggish
  • Cause you to move more slowly than usual or to need help getting around
  • Be common during active treatment and may begin to improve several weeks or a month after treatment ends
  • Persist for as long as 6 months to 1 year after treatment, or in some cases, even longer

It's important to let your care team know if you have these symptoms.


What are the symptoms of cancer-related insomnia?

A night or two of poor sleep can be annoying, but the problem normally resolves itself. With insomnia, which is a type of sleep disorder, it's difficult to fall asleep or stay asleep three or more nights a week over a long period.

Insomnia impacts your body’s ability to fight infection and increases your risk of developing anxiety and depression. If you think you have insomnia, it's important to let your care team know.

Some signs of insomnia include:

  • Difficulty sleeping most nights
  • Lying awake for hours
  • Falling asleep quickly, waking up later, and being unable to go back to sleep
  • Rarely feeling well-rested in the morning
  • Having trouble concentrating, finishing tasks, and staying awake during the day

If you had sleep problems before breast cancer

If you had sleep problems before breast cancer, you could have insomnia or another sleep disorder unrelated to breast cancer. Conditions such as low thyroid function, heart disease, and anemia (a low red blood cell count) can cause fatigue. Sleep problems can also be caused by emotional issues or medicines you take for other conditions. But if sleeping difficulty began with the cancer diagnosis or before or during treatment, it's possible that there's a connection. Whether sleep problems developed before or after diagnosis, let your care team know.


What causes breast cancer-related insomnia and fatigue?

Many factors can cause sleeping problems in people with cancer, and it can be challenging to find a single cause. Identifying possible causes will help you and your healthcare team figure out ways to help maintain your energy.

Your lifestyle

Poor sleep habits can take a toll when you are dealing with cancer. Here are some things to consider:

  • Do you go to bed and wake up at different times each day?
  • Do you drink coffee, tea, or other caffeinated beverages at night?
  • Do you engage in activities that stimulate you — action movies, video games, computer work, exercise — too close to bedtime?
  • Do you drink alcohol before bed? (It might help you fall asleep, but it keeps you from getting the deep sleep you need to feel well rested.)

Your emotions

Even with a good network of support, you may feel nervous, anxious, sad, depressed, fearful, or overwhelmed. These emotions can leave you feeling drained yet unable to sleep.

If your emotions are getting in the way of everyday function, you may have anxiety or depression, which can contribute to insomnia and fatigue. Share your feelings with your healthcare team so they can recommend supportive management strategies.

Your treatments and side effects

Here are some ways that breast cancer treatment can trigger insomnia and fatigue:

  • Radiation therapy can cause fatigue as treatment goes on, because it destroys some healthy cells along with cancer cells. Painful skin side effects, such as blistering, can interfere with sleep.
  • Chemotherapy medicines make it harder for the bone marrow to produce red blood cells, which carry oxygen through the body to cells and tissues. Having fewer red blood cells than normal is known as anemia. If cells aren’t getting enough oxygen, you may feel very tired.
  • Hormonal therapies interfere with estrogen production, causing menopausal symptoms including hot flashes, night sweats, and changes in mood, sleep, and energy.
  • Specific side effects common to treatments such as surgery, chemotherapy, hormonal therapy, and targeted therapy can also contribute to insomnia and fatigue:
    • Long periods of inactivity or bed rest while recovering from surgery or chemotherapy treatments can make you feel tired and weak.
    • Nausea and vomiting and diarrhea cause a loss of fluids and electrolytes (salts and minerals in the blood) that help maintain energy.
    • Constipation, mouth sores, or loss of appetite can make it hard to eat, which means you may not be getting enough nutrients.
    • Infection or weight changes can affect your energy level.
  • Pain caused by treatment or by cancer itself can interfere with sleep. Ongoing pain can lead to fatigue. Talk with your care team about how to control pain while maintaining your energy level.
  • Medicines to treat the side effects of cancer treatments can cause their own side effects, which can lead to fatigue or sleep problems:
    • Antidepressants, anti-nausea medicines, and pain medicines can cause fatigue.
    • Steroids, given before chemotherapy to reduce nausea or allergic reactions, can interfere with sleep.
    • Anti-anxiety medicines can add to feelings of fatigue.

Not everyone has every side effect listed above. Your care team can help you create an effective treatment plan with strategies for preventing or managing side effects, including insomnia and fatigue.


Talking with your care team about insomnia and fatigue

If you're experiencing insomnia or fatigue, your care team can help you figure out what's causing your symptoms and rule out other possible diagnoses.

Before your next appointment, write down your activities and symptoms in a notebook or journal. The information you write in your journal can help guide the conversation with your team. Here are some things to include:

  • Write down your sleeping, eating, and exercise habits, as well as any emotional changes since diagnosis and the beginning of treatment.
  • Track daily changes in fatigue or insomnia. Do symptoms vary throughout the day, or over a period of days? Do they happen on or after treatment days? Is there an increase in symptoms after physical activity or other events?
  • Rate how tired you feel on a scale of 0 to 10 (0 being no fatigue, 10 being the most exhausted you have ever felt).
  • Be as descriptive as possible so your team can find the best ways to help. Describe problems falling asleep, staying asleep, waking too early, or being unable to fall back asleep.
  • Write down any over-the-counter sleep aids you might be taking.
  • Make sure to mention pain or shortness of breath during exercise.

When you see your care team, share what you've tracked in your journal. Let them know the ways that insomnia or fatigue are interfering with your life and daily activities. You and your team will work together to find ways to manage your symptoms.

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Reviewed and updated: August 19, 2022

Reviewed by: Dianne L. Hyman, MSN, RN, OCN


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