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Brain radiotherapy and tiredness

Radiotherapy to the brain can make you feel very tired during and after treatment.

Tiredness due to brain radiotherapy

You might have radiotherapy for:

  • a tumour that started in the brain (a primary brain tumour)
  • cancer cells that have spread into the brain from another part of the body (secondary brain tumour)

You might not feel tired at the beginning of your treatment. The tiredness usually comes on gradually as you go through your treatment over a number of weeks. By the end of the course of treatment you may feel very tired.

The tiredness is a direct effect of the treatment. It is due to the body using up your energy reserves to repair healthy cells damaged by the radiotherapy. If you are taking steroids, you might also find that you feel extremely tired when you stop taking them.

Travelling to the hospital for treatment can also make you tired. Unfortunately, the tiredness doesn't go away immediately when the treatment ends. It usually carries on for at least 6 weeks.

Somnolence syndrome

In a few people, the tiredness can become very severe a few weeks after treatment has finished. You may also feel drowsy and irritable.

This is a rare side effect and is called somnolence syndrome. It is an extreme tiredness that can make you feel very drowsy and sleep for up to 20 hours a day.

You might also have headaches, a high temperature, loss of appetite, nausea, vomiting, and irritability.

Symptoms usually occur 3 to 12 weeks after the end of radiotherapy treatment and can last a few days or several weeks.

It doesn't need treatment and gets better on its own over a few weeks.

Coping with tiredness

You might feel weak and lack energy as well as being tired. It can sometimes help to sleep for a short time during the day. Rest when you need to.

Various things can help you to reduce tiredness and cope with it, for example exercise. Some research has shown that taking gentle exercise can give you more energy. It is important to balance exercise with resting.

Last reviewed: 
14 Mar 2016
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    Cancer Epidemiology, Biomarkers and Prevention (2011)

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    Clinical Journal of Oncology Nursing (2007)

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    V T DeVita and others 
    Wolters Kluwer (2015)

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