Fatigue is a condition associated with a lack of energy, tiredness or weariness. It is a condition that is separate from drowsiness, which is a feeling of the need to sleep. However, drowsiness can accompany fatigue. Fatigue is associated with a lack of motivation and can have drowsiness and apathy as symptoms of the condition. Fatigue can be a normal response to a variety of factors or it can be a sign of a more serious condition, such as a physical or psychological disorder.
Normal Response
Physical exertion can result in fatigue, especially if the exertion is beyond the scope of normal physical activity. Fatigue can result from overworking. Also, fatigue can be a normal response to lack of sleep. It can also be a normal response to stress or boredom and to pregnancy.
Psychological Problems
According to the Mayo Clinic, fatigue can result from a mental health issue such as depression or grief. Fatigue is considered a symptom under these conditions, which could result in other symptoms such as irritability and a lack of motivation.
Common Causes
According to the National Library of Medicine, the common causes of fatigue include either an overactive or underactive thyroid. An allergy that leads to asthma or hay fever is a common cause of fatigue. Sleeping disorders such as sleep apnea, narcolepsy and insomnia can result in fatigue. The use of drugs or alcohol, especially the regular use of them, is a common cause of fatigue. Anemia and persistent pain are two other common causes of fatigue.
Other Common Causes
According to the Mayo Clinic, other common causes of fatigue include caffeine use, acute liver failure, cancer, acute fatigue syndrome, chronic obstructive pulmonary disease, heart disease, kidney failure, obesity, emphysema, diabetes and unhealthy eating habits.
Chronic Fatigue Syndrome
The Centers for Disease Control and Prevention notes that the cause of chronic fatigue syndrome is unknown, despite being the subject of intensive research. However, there are some potential causes that have been suggested, including viral infection, stress and toxins.
