Black Cat Blues

Caffeine is a central nervous system stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity: caffeine is the world's most widely consumed psychoactive substance. In North America, 90% of adults consume caffeine daily.

Humans have consumed caffeine since the Stone Age. Early peoples found that chewing the seeds, bark, or leaves of certain plants had the effects of easing fatigue, stimulating awareness, and elevating mood. Only much later was it found that the effect of caffeine was increased by steeping such plants in hot water. Many cultures have legends that attribute the discovery of such plants to people living many thousands of years ago. The early history of coffee is obscure, but a popular myth traces its discovery to Ethiopia, where Coffea arabica originates. According to this myth, a goatherder named Kaldi observed goats that became elated and sleepless at night after browsing on coffee shrubs and, upon trying the berries that the goats had been eating, experienced the same vitality.

Caffeine is an ergogenic: increasing the capacity for mental or physical labor. A study conducted in 1979 showed a 7% increase in distance cycled over a period of two hours in subjects who consumed caffeine compared to control tests. Other studies attained much more dramatic results; one particular study of trained runners showed a 44% increase in "race-pace" endurance, as well as a 51% increase in cycling endurance, after a dosage of 9 milligrams of caffeine per kilogram of body weight. The extensive boost shown in the runners is not an isolated case; additional studies have reported similar effects.

Caffeine is a drug that in large amounts, especially over an extended period of time, can lead to a condition termed "caffeinism." Caffeinism usually combines physical addiction with a wide range of unpleasant physical and mental conditions including nervousness, irritability, anxiety, tremulousness, muscle twitching (hyperreflexia), insomnia, and heart palpitations. (Under a rigid definition of addiction, meaning a process of escalating use, "caffeine dependency" would be a more descriptive term. However, under the widely accepted definition "chronic pattern of behavior that is perceived to be difficult to quit," caffeine may be said to be addictive.) Furthermore, because caffeine increases the production of stomach acid, high usage over time can lead to peptic ulcers and other diseases. However, since both "regular" and decaffeinated coffees have also been shown to stimulate the gastric mucosa and increase stomach acid secretion, caffeine is probably not the only component of coffee responsible.

Long-term overuse of caffeine can elicit a number of psychiatric disturbances. Two such disorders recognized are caffeine-induced sleep disorder and caffeine-induced anxiety disorder. In the case of caffeine-induced sleep disorder, an individual regularly ingests high doses of caffeine sufficient to induce a significant disturbance in his or her sleep, sufficiently severe to warrant clinical attention. In some individuals, the large amounts of caffeine can induce anxiety severe enough to necessitate clinical attention. This caffeine-induced anxiety disorder can take many forms, from generalized anxiety, to panic attacks, obsessive-compulsive symptoms, or even phobic symptoms. Because this condition can mimic organic mental disorders, such as panic disorder, generalized anxiety disorder, bipolar disorder, or even schizophrenia, a number of medical professionals believe caffeine-intoxicated people are routinely misdiagnosed and unnecessarily medicated when the treatment for caffeine-induced psychosis would simply be to withhold further caffeine. A Study in the British Journal of Addiction concluded that caffeinism, although infrequently diagnosed, may afflict as many as one person in ten of the population.

Several large studies have shown that caffeine intake is associated with a reduced risk of developing Parkinson's disease in men, but studies in women have been inconclusive.

- scriptor (thanks to Wikipedia)