Fatigue is unfortunately, another common FND symptom. Fatigue is also known as exhaustion and tiredness.
Unlike weakness, fatigue can be less severe with periods of rest. Fatigue is know to have physical or mental causes. Which I have outlined below:
Physical fatigue is the temporary inability of a muscle to maintain its maximum physical performance, and is made more severe by high intense physical exercise.
Mental fatigue is a short-term decrease in maximal cognitive performance resulting from long periods of cognitive activity. It can manifest as drowsiness, lack of energy and or enthusiasm.
Medically, fatigue has many possible causes. Fatigue is considered a symptom, rather than a sign because, it is a subjective feeling reported by a sufferer, rather than an objective one that can be observed by others. Fatigue and 'feelings of fatigue' are often confused.