Fatigue or tiredness is a physical or mental feeling. Tiredness is usually indicated by a person feeling sleepy; it can also involve feeling weak, slow or "draggy". They may yawn, and may find it difficult to keep the eyes open. Usual "normal" fatigue goes away when after resting, napping, or sleeping.
Fatigue may be caused by any number of things, from the day-to-day acts of simply being awake for a while or exercising, to physical illness, anaemia, blood loss, low blood pressure (hypotension), hypothyroidism, abnormal cortisol levels, physical or mental exhaustion, jet lag,medication side effects, malnutrition, starvation, mental illness, drug or alcohol use, stress, boredom, or any number of other things.
