Caffeine and fatigue

Experimental evidence suggests that effects of caffeine on task performance, subjective reactions, and psychophysiological measures are state dependent. Caffeine is said to have, nonspecific arousal-enhancing effects and specific cognitive effects. 1, 2 If true, especially in states of fatigue, energizing effects of caffeine should be found more prominently. Some studies could or do show that caffeine may improve performance beyond optimum levels. 3-6 However, in states of overarousal, such as agitation, excitement, or strenuous exercise, caffeine should deteriorate performance. In this chapter, the relationship of caffeine and fatigue will be discussed.