Fatigue (also called
exhaustion,
tiredness,
languidness,
languor,
lassitude, and
listlessness) is a subjective feeling of tiredness which is distinct from
weakness, and has a gradual onset. Unlike weakness, fatigue can be alleviated by periods of
rest. Fatigue can have physical or mental causes. Physical fatigue is the transient inability of a
muscle to maintain optimal physical performance, and is made more severe by intense
physical exercise. Mental fatigue is a transient decrease in maximal cognitive performance resulting from prolonged periods of cognitive activity. It can manifest as
somnolence,
lethargy, or
directed attention fatigue.
