What Can Cause Fatigue?

Fatigue has a number of potential underlying causes.

Fatigue is a constant, lingering feeling of exhaustion. It may be severe enough to limit a person’s daily routine and productivity. Fatigue may be a normal response to a tiring routine, extreme physical activity, emotional stress, boredom or lack of sleep. If adequate rest does not make the fatigue go away or if the fatigue lasts for six months or longer, it is called severe or chronic fatigue syndrome. Such fatigue may be due to other medical conditions. Common signs related to fatigue include

• Weakness
• Constantly tired or exhausted
• Difficulty concentrating and/or difficulty starting and completing tasks
• Fainting or loss of consciousness (syncope) or near syncope
• Palpitations (rapid heartbeat)
• Dizziness or vertigo 
• Unexplained weight loss
• Generalized body aches and headaches

Fatigue can also be caused by a number of factors working in combination. The causes that may trigger fatigue include

• Lifestyle-related causes: Alcohol, smoking, or drugs or lack of regular exercise can lead to feelings of fatigue. Lack of sleep and improper diet can also increase fatigue.
• Shift worker fatigue: Individuals who get up early for work (slight sleep phase delay) or those who work late (slight sleep phase advance) may have disturbed sleep. These people also have misalignment of the body clock. Such conditions are a common cause of fatigue, especially if the shifts alternate frequently.
• Workplace-related causes: Workplace stress is known to be the most common cause of fatigue.
• Emotional or psychiatric concerns: Fatigue is a common symptom of mental health problems, such as anxiety, depression and grief. It may be accompanied by irritability and lack of motivation. Personal illness or injury, illnesses or injuries in the family, too many commitments (for example, working two jobs) or financial problems can cause fatigue.
• Medications: Antidepressants, anti-anxiety medications, sedative medications, medication and drug withdrawal, antihistamines, steroids and some blood pressure medications may cause fatigue as a side effect.
• Myalgic encephalomylitis or chronic fatigue syndrome: This is a complex condition in which there is constant fatigue for at least six months with post-exertional exhaustion and poor-quality sleep. Other than these symptoms, the person has memory problems or other vague symptoms that get better when lying down (orthostatic intolerance).

Apart from the aforementioned factors, below are few medical problems that may cause fatigue

• Infectious: Usually, infections are one of the main reasons for fatigue. Examples include human immunodeficiency virus (HIV), hepatitis, tuberculosis, etc. 
• Metabolic/endocrine: Metabolic- or hormone-related changes are the common causes of fatigue, especially in women. Examples include pregnancy, thyroid problems, diabetes, electrolyte abnormalities, kidney disease, liver disease, etc.
• Heart and lung diseases: Heart and lung disease are some of the most common causes of fatigue in older people. Examples include heart failure, coronary artery disease, chronic obstructive pulmonary disease (COPD), asthma, arrhythmias, pneumonia, etc. 
• Vitamin deficiencies: These include vitamin B12 deficiency, vitamin D deficiency, folic acid deficiency and iron deficiency.
• Allergies: Allergies are a common cause of severe fatigue. Allergic rhinitis, food allergies, and environmental and seasonal allergies are common examples that may cause severe fatigue.
• Other causes: These include cancer, chemotherapy, radiation therapy, arthritis, systemic lupus, fibromyalgia, sleep apnea and obesity.

Lifestyle modifications can help a person relieve symptoms of fatigue. A few common modifications include

• Avoiding alcohol, nicotine and drug use
• Getting enough undisturbed sleep each night, at least seven hours .
• A job change may be required if fatigue brought on by shifts becomes extreme.
• Eating a healthy and well-balanced diet
• Drinking plenty of water throughout the day
• Getting  regular exercise to keep the body fit
• Practicing Relaxation techniques such as yoga or meditation
• Maintaining a reasonable work and personal schedule
• Decreasing stressors in life by taking a break or a vacation or resolving relationship and financial problems
• Treating the underlying cause, if any
• Chronic fatigue syndrome not responding to the measures above may need medication. Modafinil and armodafinil are drugs available to improve wakefulness and make patients feel refreshed. These are reserved in extreme cases however and should not be used as the primary treatment for fatigue.

Not everyone needs medical attention to treat symptoms of fatigue. Simple lifestyle modification as elaborated above can relieve fatigue. However, in few conditions, medical attention may be required if any of the following are present

• Confusion or dizziness
• Blurred vision
• Fever
• Little or no urine output or recent swelling and weight gain 
• Thoughts of harming onerself or of committing suicide
• Unintentional weight loss
• Constipation, dry skin and intolerance to cold
• Unable to sleep or sleep disturbances
• Severe and recurrent headaches
• Medication side effects