Fatigue can result from a mental or physical health condition, medication use, or chronic pain, among other reasons. Treatment involves managing the underlying cause.

Physical and mental fatigue are different, but they often occur together. Repeated physical exhaustion can lead to mental fatigue over time.

When fatigue affects safety, it becomes a public health concern. People with severe fatigue may act similarly to those who are intoxicated.

Insufficient sleep, particularly when it occurs for a long time, can also lead to fatigue. Officials recommend that adults get 7 to 8 hours of sleep each night, but as many as 1 in 3 Americans do not get this much.

Eating a balanced diet and getting regular physical activity can help reduce fatigue for many people. Treating the underlying cause of fatigue, whether this is not enough sleep or a health condition, also helps.

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There are two main types of fatigue: physical and mental.

Someone with physical fatigue may find it physically hard to do the things they usually do, such as climbing the stairs. Symptoms include muscle weakness, and diagnosis may involve completing a strength test.

With mental fatigue, someone may find it harder to concentrate and focus. They may feel sleepy or have difficulty staying awake while working.

Sleepiness can occur when someone does not get enough good-quality sleep or when they lack stimulation. It can also indicate a health condition that interferes with sleep, such as sleep apnea or restless legs syndrome.

Sleepiness is more likely to be short-term than fatigue. It is usually treatable with regular and consistent sleep.

However, healthcare professionals typically associate fatigue — especially when it is chronic — with a health condition or problem. It may also be its own chronic condition, called chronic fatigue syndrome, or myalgic encephalomyelitis.

It can be challenging to diagnose fatigue as it is a nonspecific symptom with multiple potential causes. This means it can take quite a long time for a healthcare professional to diagnose the underlying cause.

Mental health issues

Fatigue is a main symptom of clinical depression, either due to the depression itself or associated problems, such as insomnia.

Stress is another common cause of fatigue. Fatigue can also result from the following mental health issues:

Endocrine and metabolic reasons

Health conditions and other factors that affect hormones may cause fatigue. These include:

Drugs and medications

Certain drugs and medications can cause fatigue, including:

Medication withdrawal or changes in dosage can also cause fatigue until the body adjusts.

Heart and lung conditions

Heart and lung conditions can affect blood flow in the body or cause inflammation and may lead to fatigue. These include:

Sleep problems

The following sleep factors can also lead to fatigue:

Chemicals and substances

Vitamin deficiencies, mineral deficiencies, and poisoning can all affect sleep and cause fatigue.

Consuming caffeinated drinks or alcohol can also disrupt sleep, especially close to bedtime. Using products containing nicotine can also disrupt sleep.

Medical conditions

Several medical conditions can cause fatigue, including:

Fatigue can also be a symptom of infection. Some infections that cause extreme tiredness include:

Chronic pain

People with chronic pain may wake up frequently throughout the night. They may also wake up feeling tired and poorly rested, having been unable to get good-quality sleep.

The combination of chronic pain and a lack of sleep can cause persistent tiredness and fatigue.

A 2024 review suggests that around 21% of people with obstructive sleep apnea also have fibromyalgia, which contributes to fatigue.

Being overweight or underweight

Excess body weight increases the risk of fatigue by increasing the risk of conditions that cause fatigue, such as diabetes or sleep apnea.

Carrying more weight and experiencing joint or muscle pain can lead to or exacerbate fatigue.

Similarly, people who are underweight may tire easily, depending on the cause of their condition. Eating disorders, cancer, chronic diseases, and an overactive thyroid can all cause weight loss, as well as excessive tiredness and fatigue.

Too much or too little activity

Fatigue can make it challenging to exercise, and a lack of exercise may cause further fatigue. A lack of exercise may eventually cause deconditioning, making it harder and more tiring to perform a physical task.

Fatigue can also affect people after prolonged, intense mental or physical activity.

The main symptom of fatigue is exhaustion with physical or mental activity. People do not feel refreshed after resting or sleeping. It might also be hard for them to carry out their daily activities, including work, household chores, and caring for others.

Fatigue’s symptoms may be physical, mental, or emotional. Examples include:

Symptoms may worsen after exertion.

Diagnosis can be challenging, as the causes and symptoms of fatigue are varied and nonspecific.

A doctor may ask questions about:

  • the qualities of the fatigue
  • the patterns of the fatigue
  • whether or not taking a nap helps
  • the quality of the person’s sleep
  • the person’s emotional state and stress levels

People can aid their diagnosis by keeping a record of the total hours they sleep each night and how often they wake up each night.

The doctor will carry out a physical examination to check for signs of illness and ask the person which medications they are taking, if any.

They will also ask about lifestyle habits, including the person’s diet, caffeine use, drug use, alcohol consumption, and work and sleep patterns.

Diagnostic tests

Diagnostic tests can help determine the underlying cause of the fatigue. Urine tests, imaging scans, mental health questionnaires, and blood tests may be necessary depending on other symptoms.

These tests can help rule out physical causes, such as infections, hormonal problems, anemia, liver problems, or kidney problems. The doctor may also order a sleep study to rule out a sleeping disorder.

If they diagnose an illness, they will suggest appropriate treatments.

To treat fatigue effectively, a doctor needs to find and diagnose the underlying cause.

Sleep habits

Getting enough sleep is an important part of managing fatigue. To practice good sleep hygiene, people should:

  • Aim to go to bed and wake up at the same time each day, even on days off.
  • Set the bedroom temperature at a comfortable level.
  • Make sure the room is dark and quiet.
  • Avoid screen time an hour before sleeping, as the light and sounds from a television, computer, or phone can stimulate brain activity and affect sleep quality.
  • Avoid eating shortly before going to bed.
  • As bedtime approaches, try to slow down both physically and mentally. Taking a warm bath or listening to some soothing music can help clear the mind of stressful and worrying thoughts before going to sleep.

Keeping a sleep diary to detect patterns may also help.

Diet

Diet can affect energy levels. Maintaining a moderate and well-balanced diet may improve health and sleep. People can try the following:

  • Eat small, frequent meals throughout the day.
  • Eat snacks that are low in added sugar.
  • Avoid highly processed food and follow a healthy diet.
  • Consume plenty of fresh fruits and vegetables.
  • Avoid caffeine in the afternoon and evening.

Physical activity

Getting regular physical activity can help reduce fatigue and improve sleep.

Those who have not been physically active for some time should introduce exercise gradually. A doctor or sports therapist can help.

People should exercise during the time of day that is most productive for them.

Yoga and mindfulness

A 2022 review suggests that mindfulness can significantly improve cancer-related fatigue, depression, and anxiety.

A 2023 study suggests that mindfulness may help to reduce any association between fatigue and negative emotional responses at a neural level.

Similarly, a 2024 study suggests that movement-based mindful exercises, including yoga, tai chi, and qigong, may help reduce fatigue due to chronic fatigue syndrome or post-COVID syndromes.

A 2023 review suggests that driver fatigue contributes to 20% of motor vehicle accidents.

If a driver notices that they are doing any of the following, they should pull over and take a nap or change drivers:

  • yawning and blinking
  • not remembering the last few miles they have driven
  • missing an exit
  • drifting across the lane
  • driving onto a rumble strip
  • having trouble staying focused

A range of health conditions and lifestyle factors, such as diabetes, depression, and chronic pain, among others, can cause fatigue.

If fatigue and sleepiness affect a person’s daily life and none of the tips in this article work, they should see a doctor for advice.

To help with diagnosis, people can keep a diary of their sleep habits and symptoms. After making a diagnosis, a doctor will be able to suggest some appropriate treatment options.