Anxiety and depression are the most common psychological causes of fatigue in cancer patients.
The emotional stress of cancer can cause physical problems, including fatigue. It's common for cancer patients to have changes in moods and attitudes. Patients may feel anxiety and fear before and after a cancer diagnosis. These feelings may cause fatigue. The effect of the disease on the patient's physical, mental, social, and financial well-being can increase emotional distress.
About 15% to 25% of patients who have cancer get depressed, which may increase fatigue caused by physical factors. The following are signs of depression:
- Feeling tired mentally and physically.
- Loss of interest in life.
- Problems thinking.
- Loss of sleep.
- Feeling a loss of hope.
Some patients have more fatigue after cancer treatments than others do.
Fatigue may be increased when it is hard for patients to learn and remember.
During and after cancer treatment, patients may find they cannot pay attention for very long and have a hard time thinking, remembering, and understanding. This is called attention fatigue. Sleep helps to relieve attention fatigue, but sleep may not be enough when the fatigue is related to cancer. Taking part in restful activities and spending time outdoors may help relieve attention fatigue.
Not sleeping well may cause fatigue.
Some people with cancer are not able to get enough sleep. The following problems related to sleep may cause fatigue:
- Waking up during the night.
- Not going to sleep at the same time every night.
- Sleeping during the day and less at night.
- Not being active during the day.
Poor sleep affects people in different ways. For example, the time of day that fatigue is worse may be different. Some patients who have trouble sleeping may feel more fatigue in the morning. Others may have severe fatigue in both the morning and the evening.
Even in patients who have poor sleep, fixing sleep problems does not always improve fatigue. A lack of sleep may not be the cause of the fatigue. See the PDQ summary on Sleep Disorders for more information.
Medicines other than chemotherapy may add to fatigue.
Patients may take medicines for cancer symptoms, such as pain, or conditions other than the cancer. These medicines may cause the patient to feel sleepy. Opioids, antidepressants, and antihistamines have this side effect. If many of these medicines are taken at the same time, fatigue may be worse.
Taking opioids over time may lower the amount of sex hormones made in the testicles and ovaries. This can lead to fatigue as well as sexual problems and depression.