Fatigue can mean feeling tired, sleepy or lacking energy. Fatigue may be due to medical causes, lifestyle or emotional concerns or stress. Depression, anxiety or grief can all cause fatigue. Too little or too much sleep can cause fatigue. Medical causes of fatigue may include flu, glandular fever, anaemia, sleep disorders such as sleep apnoea or restless leg syndrome, CFS/ME (formerly known as chronic fatigue syndrome or myalgic encephalopathy), hypothyroidism, heart problems, cancer and other conditions.
Fatigue is a feeling of weariness, tiredness, or lack of energy that does not go away when you rest. People may feel fatigued – in body or mind (physical fatigue or psychological fatigue).
With physical fatigue, your muscles cannot do things as easily as they used to. You might notice this when you climb stairs or carry bags of groceries. With psychological fatigue, it may be difficult to concentrate for as long as you used to. In severe cases, you might not feel like getting out of bed in the morning and doing your regular daily activities.
So what's making you so tired all the time? Most of the time, fatigue can be traced to one or more of your habits or routines. Fatigue can be a normal and important response to physical exertion, poor eating habits, emotional stress, boredom, or lack of sleep. In some cases, however, fatigue is a symptom of an underlying medical problem that requires medical treatment.
When fatigue is not relieved by enough sleep, good nutrition, or a low-stress environment, it should be evaluated by your doctor.
Fatigue can cause a vast range of other physical, mental and emotional symptoms including:
- Chronic tiredness or sleepiness
- Sore or aching muscles
- Muscle weakness
- Slowed reflexes and responses
- Impaired decision-making and judgement
- Moodiness, such as irritability
- Impaired hand-to-eye coordination
- Appetite loss
- Reduced immune system function
- Blurry vision
- Short-term memory problems
- Poor concentration
- Reduced ability to pay attention to the situation at hand
- Low motivation.
A range of causes
The wide range of causes that can trigger fatigue include:
- Medical causes – unrelenting exhaustion may be a sign of an underlying illness, such as a thyroid disorder, heart disease or diabetes.
- Lifestyle-related causes – feelings of fatigue often have an obvious cause, such as sleep deprivation, overwork or unhealthy habits.
- Emotional concerns and stress – fatigue is a common symptom of mental health problems, such as depression and grief, and may be accompanied by other signs and symptoms, including irritability and lack of motivation.
Many diseases and disorders can trigger fatigue, including:
- The flu
- Glandular fever
- Sleep disorders, such as sleep apnoea or restless leg syndrome
- CFS/ME (formerly known as chronic fatigue syndrome or myalgic encephalopathy)
- Chronic pain
- Coeliac disease
- Addison’s disease
- Parkinson’s disease
- Heart problems
- Certain medications.
Lifestyle related causes
Common lifestyle choices that can cause fatigue include:
- Lack of sleep – typically adults need about eight hours of sleep each night. Some people try to get by on fewer hours of sleep.
- Too much sleep – adults sleeping more than 11 hours per day can lead to excessive daytime sleepiness.
- Alcohol and drugs – alcohol is a depressant drug that slows the nervous system and disturbs normal sleep patterns. Other drugs, such as cigarettes and caffeine, stimulate the nervous system and can cause insomnia.
- Sleep disturbances – disturbed sleep may occur for a number of reasons, for example, noisy neighbours, young children who wake in the night, a snoring partner, or an uncomfortable sleeping environment such as a stuffy bedroom.
- Lack of regular exercise and sedentary behaviour – physical activity is known to improve fitness, health and wellbeing, reduce stress, and boost energy levels. It also helps you sleep.
- Poor diet – low kilojoule diets, low carbohydrate diets or high energy foods that are nutritionally poor don’t provide the body with enough fuel or nutrients to function at its best. Quick fix foods, such as chocolate bars or caffeinated drinks, only offer a temporary energy boost that quickly wears off and worsens fatigue.
- Individual factors – personal illness or injury, illnesses or injuries in the family, too many commitments (for example, working two jobs) or financial problems can cause fatigue.
Workplace related causes
Common workplace issues that can cause fatigue include:
- Shift work – the human body is designed to sleep during the night. This pattern is set by a small part of the brain known as the circadian clock. A shift worker confuses their circadian clock by working when their body is programmed to be asleep.
- Poor workplace practices – can add to a person’s level of fatigue. These may include long work hours, hard physical labour, irregular working hours (such as rotating shifts), stressful work environment (such as excessive noise or temperature extremes), boredom, working alone with little or no interaction with others, or fixed concentration on a repetitive task.
- Workplace stress – can be caused by a wide range of factors including job dissatisfaction, heavy workload, conflicts with bosses or colleagues, bullying, constant change, or threats to job security.
- Burnout – can be described as striving too hard in one area of life while neglecting everything else. ‘Workaholics’, for example, put all their energies into their career, which puts their family life, social life and personal interests out of balance.
- Unemployment – financial pressures, feelings of failure or guilt, and the emotional exhaustion of prolonged job hunting can lead to stress, anxiety, depression and fatigue.
Studies suggest that psychological factors are present in at least 50 per cent of fatigue cases. These may include:
- Depression – this illness is characterised by severe and prolonged feelings of sadness, dejection and hopelessness. People who are depressed commonly experience chronic tiredness.
- Anxiety and stress – a person who is chronically anxious or stressed keeps their body in overdrive. The constant flooding of adrenaline exhausts the body, and fatigue sets in.
- Grief – losing a loved one causes a wide range of emotions including shock, guilt, depression, despair and loneliness.
Diagnosis can be difficult
Since fatigue can present a vast range of symptoms and be caused by many different factors working in combination, diagnosis can be difficult. Your doctor may diagnose fatigue using a number of tests including:
- Medical history – recent events such as childbirth, medication, surgery or bereavement may contribute to fatigue.
- Physical examination – to check for signs of illness or disease. The doctor may also ask detailed questions about diet, lifestyle and life events.
- Tests – such as blood tests, urine tests, x-rays and other investigations. The idea is to rule out any physical causes, for example anaemia, infection or hormonal problems.
Where to get help
- Your doctor
Things to remember
- Fatigue can be caused by a number of factors working in combination, such as medical conditions, unhealthy lifestyle choices, workplace problems and stress.
- Fatigue is a known risk factor in motor vehicle and workplace accidents.
- Always see your doctor for diagnosis if you are suffering from chronic tiredness.
You might also be interested in:
- Chronic fatigue syndrome (CFS).
- Fatigue fighting tips.
- Jet lag.
- Sleep - common disorders.
- Sleep - insomnia.
- Sleep apnoea.
- Sleep deprivation.
- Sleep hygiene.
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Last reviewed: June 2014
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