A condition marked by extreme tiredness and inability to function due lack of energy. Fatigue may be acute or chronic.

A feeling of weariness, sleepiness or irritability after a period of mental or bodily activity. Seen in depression, anxiety, neurasthenia and somatoform disorders.

A lack of energy. A decrease over time in the ability to perform a physical or mental task.

A state of generalized weakness with a pronounced inability to summon sufficient energy to accomplish daily activities.

A subjective feeling of tiredness characterized by a lack of energy and motivation.

Fatigue is a feeling of weariness, tiredness, or lack of energy. It can interfere with your usual daily activities. Fatigue can be a normal response to physical activity, emotional stress, boredom, or lack of sleep. But sometimes it can be a sign of a mental or physical condition. If you have been feeling tired for weeks, contact your health care provider. They can help you find out what's causing your fatigue and recommend ways to relieve it. Fatigue itself is not a disease; it's a symptom. It can have many different causes, including pregnancy and various medical problems, treatments, and lifestyle habits such as: Medical problems: Chronic (long-lasting) diseases such as diabetes, COPD (chronic obstructive pulmonary disease), and heart, liver, kidney and thyroid diseases; Untreated pain and diseases like fibromyalgia; Anemia; Infections; Parkinson's disease; Sleep apnea and other sleep disorders; Recent stroke; Mental disorders such as depression and anxiety.; Treatments: Cancer treatments such as chemotherapy, radiation, and bone marrow transplants; Recovering from major surgery; Taking certain medicines, such as antidepressants, antihistamines, and medicines for nausea and pain.; Lifestyle habits: Not getting enough sleep; Staying up too late; Drinking too much alcohol; Substance use; Having too much caffeine (which can keep you from getting a good night's sleep); Getting too little or too much exercise. . Overwhelming fatigue is part of a disorder called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The fatigue caused by this disorder is different from a tired feeling that goes away after you rest. Instead, the fatigue in ME/CFS lasts a long time, does not get better with rest, and limits your ability to do ordinary daily activities. If you've had fatigue that does not get better after several weeks, call your provider. They will ask questions about your sleep, daily activities, appetite, and exercise. They will likely do a physical exam and order lab tests. Once they decide on a diagnosis, they can tell you what treatments might help. You can also make some lifestyle changes to feel less tired: Get regular physical activity; Improve your sleep habits; Stop smoking (if you smoke), since smoking is linked to many diseases that can cause fatigue; Manage stress; Eat a healthy diet and avoid alcohol. It also may be helpful for you to keep a fatigue diary. This can help you find patterns throughout the day, such as when you feel more tired and when you have more energy. It can also help you plan for activities that may give you more energy. NIH: National Institute on Aging

Overall tiredness and lack of energy.

State of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli.

The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli.

Unusual tiredness and inability to perform usual activities.

(fatigue (lassitude)) A state of exhaustion usually caused by various etiologies such as a period of mental or bodily activity, sleep deprivation, medications, chronic disease, or other factors.

A disorder characterized by a state of generalized weakness with a pronounced inability to summon sufficient energy to accomplish daily activities.

Fatigue occurs most often as part of a symptom complex, but even when it is the sole or main presenting symptom, fatigue is one of the most common symptoms.

Fatigue, specific form of human inadequacy in which the individual experiences an aversion to exertion and feels unable to carry on. Such feelings may be generated by muscular effort; exhaustion of the energy supply to the muscles of the body, however, is not an invariable precursor. Feelings of...