Fatigue is one of the most common problems after a brain injury. In the early stages of recovery following brain injury, the person may experience higher levels of fatigue. However, the problem may reduce over time.
Fatigue can have a negative effect on physical functioning, activities of daily living, cognitive functioning, communication, mental state and behaviour. A vicious cycle may develop in which physical and/or mental effort leads to fatigue, which in turn leads to increased difficulties managing everyday tasks and a further increase in levels of fatigue.
After brain injury the person may experience more than one kind of fatigue i.e. physical fatigue and cognitive (mental) fatigue.
Physical Fatigue
Following brain injury the body often needs to work harder to do things which were previously effortless. This leads to the person experiencing fatigue. Physical impairments related to brain injury such as spasticity, dystonia, muscle weakness etc will exacerbate levels of physical fatigue. In turn, physical fatigue may further exacerbate physical impairments.
Following brain injury the person may experience problems with fatigue over a prolonged period 
resulting in deconditioning i.e. the person has lost physical fitness and stamina due to a period of illness, immobility and/or inactivity. Deconditioning is a complex physiological process, in which reduced use of the body’s cardiovascular, neuromuscular and musculoskeletal systems leads to a decrease in the person’s ability to tolerate physical activity over time. Deconditioning leads to a reduction in the body’s capacity for exercise, a reduction in strength and an increase in the effort required for activity. Over time physical effort leads to the person experiencing ever increasing difficulties managing even normal everyday activities.
It is important to note that many patients who experience ongoing fatigue may develop unhelpful health beliefs e.g. they are unable to tolerate activity and/or participating in activity is harmful. These beliefs may potentially exacerbate and maintain the problem.
Cognitive (Mental) Fatigue
Cognitive fatigue refers to a reduction in cognitive functioning as a result of prolonged/excessive mental effort. Following a significant brain injury with associated cognitive impairment, mental tasks which were previously automatic and not effortful will require more conscious effort to complete. This may lead to the person experiencing cognitive fatigue, frequently even following seemingly ‘simple’ cognitive demands. The individual has to work harder to think and stay focused, which may lead to further mental exhaustion leading to:
- Increased attentional difficulties.
- Decreased mental flexibility.
- Increased problems thinking clearly.
- Exacerbation of confusion.
- Further impairment of memory.
- Deterioration in communication abilities.
- Increased behavioural difficulties.
A reduction in both cognitive and physical demands may help to support the person who experiences fatigue. It is important to remember that problems of cognitive overload and over stimulation (e.g. a noisy, busy environment) may contribute to cognitive fatigue in some people. Some judgement is required with regard to discriminating between levels of stimulation which are beneficial for the person and potentially overwhelming/fatiguing levels of stimulation. Be aware however, that habitual avoidance of busy environments may lead to an exacerbation of the problem over time and a reduction in the ability of the person to tolerate higher levels of stimulation.
There are a number of potential contributory factors to be considered if a person experiences high levels of fatigue following brain injury and appropriate intervention initiated as necessary. These factors may include:
- Medical conditions such as anaemia, thyroid dysfunction, repeated infections etc.
- Side effects of sedative medication (Benzodiazepines and Antipsychotic medication) and some antidepressants (e.g. Mirtazapine). Seek medical advice.
- Depressive disorder.
- Disturbed sleep pattern related to the neurological damage caused by the brain injury.
- Sleep disturbance related to environmental factors e.g. living in a noisy ward environment or with other brain injured patients who may cause disturbance during the night.
- Sleep disturbance arising from physical causes e.g. discomfort, pain, feeling too cold/hot etc.
- Supporting people to do less in the belief that this is of assistance may have the consequence of exacerbating levels of fatigue.