Fatigue is more than just tiredness. Fatigue can make it hard to get out of bed in the morning and prevent a person from fulfilling their daily tasks.
Physical and mental fatigue are different, but they often occur together. Repeated physical exhaustion can lead to mental fatigue over time.
Poor sleep, particularly when it occurs for a long time, can also lead to fatigue. Officials recommend that adults get 7–8 hours of sleep each night.
Eating a healthful diet and getting regular physical activity can help reduce fatigue for many people. Treating the underlying cause of fatigue, whether this is poor sleep or a health condition, also helps.
When fatigue affects safety, it becomes a public health concern. People with severe fatigue may act similarly to those who are intoxicated.
There are two main types of fatigue: physical and mental.
A person 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, a person may find it harder to concentrate on things and stay focused. They may feel sleepy or have difficulty staying awake while working.
Is it sleepiness or fatigue?
Sleepiness can occur when a person does not get enough good quality sleep, or when they have a lack of stimulation. It can also be a symptom of 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, fatigue — especially when it is chronic — is often associated with a health condition or problem. It may also be its own chronic condition, called chronic fatigue syndrome, or myalgic encephalomyelitis.
Fatigue is associated with many health conditions and lifestyle factors. The sections below will outline these in more detail.
Mental health issues
Fatigue is a common symptom of clinical depression, either due to the depression itself or associated problems, such as insomnia.
Fatigue can also result from the following mental health issues:
- bereavement and grief
- eating disorders
- emotional exhaustion or burnout
- life events, such as moving home or getting a divorce
Endocrine and metabolic reasons
Health conditions and other factors that affect hormones can cause fatigue. These include:
- Cushing’s syndrome
- kidney disease
- electrolyte problems
- thyroid conditions
- hormonal contraception, including birth control pills and the implant
Medication withdrawal can also cause fatigue until the body adjusts. Changes in dosage can also be a cause.
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:
- chronic obstructive pulmonary disease
- valvular heart disease
- coronary heart disease
- congestive heart failure
The following sleep factors can also lead to fatigue:
- working late
- working shifts
- jet lag
- sleep apnea
- reflux esophagitis
Chemicals and substances
Vitamin deficiencies, mineral deficiencies, and poisoning can all affect sleep and cause fatigue.
Consuming caffeinated beverages can also disrupt normal sleep, especially close to bedtime. Using products containing nicotine can also disrupt sleep.
Several medical conditions can cause fatigue, including:
- high blood pressure
- heart disease
- chronic fatigue syndrome
- weakened immune system function
- systemic lupus
- rheumatoid arthritis
- gastroesophageal reflux disease
- inflammatory bowel disease
- cancer and cancer treatments, including chemotherapy and radiation therapy
- massive blood loss
Fatigue can also be a symptom of infection. Some infections that cause extreme tiredness include:
- infectious mononucleosis
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.
Fibromyalgia and sleep, half of the individuals with fibromyalgia also had sleep apnea, which contributes to fatigue.
Being overweight or underweight
Overweight increases the risk of fatigue by increasing the risk of conditions that have fatigue as a common symptom, such as diabetes or sleep apnea.
Carrying more weight and experiencing joint or muscle pain can lead to or exacerbate fatigue.
Similarly, people with 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
A person with fatigue may not feel able to exercise, and a lack of exercise can 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 healthy individuals after prolonged, intense mental or physical activity.
The main symptom of fatigue is exhaustion with physical or mental activity. A person does 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.
The symptoms of fatigue may be physical, mental, or emotional.
Common symptoms associated with fatigue can include:
- aching or sore muscles
- apathy and a lack of motivation
- daytime drowsiness
- difficulty concentrating or learning new tasks
- gastrointestinal problems, such as bloating, abdominal pain, constipation, or diarrhea
- irritability or moodiness
- slowed response time
- vision problems, such as blurriness
Symptoms tend to get worse after exertion. They may appear a few hours after activity or exercise, or possibly on the next day.
Diagnosis can be difficult, as the causes and symptoms of fatigue are varied and nonspecific.
The doctor may ask questions relating to:
- the qualities of the fatigue
- the patterns of the fatigue, such as the times of day when the symptoms are worse or better and whether or not taking a nap helps
- the quality of the person’s sleep
- the person’s emotional state and stress levels
A person 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 using, 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.