Caffeine is a methylated xenthine discovered in 1819 by Friedrich Ferdinand Runge, a German chemist. Sources of Caffeine include beans, fruit and leaves of some plants. Caffeine available for human consumption is most commonly extracted from the coffee plant cherries and tea bush leaves, as well as foods and drinks that contain products derived from the kola nut. Caffeine can temporarily reduce the sensation of being tired; however, this does not mean that it eliminates the need for sleep. Generally, twenty five to fifty milligrams of caffeine is enough for most consumers to report an increase in alertness and arousal. Caffeine should be not be consumed by those with fecal incontinence as it relaxes the internal anal sphincter muscles.