Caffeine is the most widely used and available drug in use today. Classified as a stimulant because of the effects on the central nervous system in producing increased alertness and energy and decreased feelings of fatigue, the positive effects also come with negative effects. You can find caffeine in drinks, in workout supplements, in medications and concentrated in tablets sold to keep you awake.
Alertness is a side effect of consuming caffeine, which is a primary reason people drink coffee in the morning. The Coffee Science Information Centre has shown that average doses caffeine of 100 to 200 mg increases mental alertness and performance of tasks. Although Griffith and Mumford in “Caffeine: A Drug of Abuse?” found in their study that heavy caffeine users did not report higher levels of alertness than non-caffeine users, this could be attributed to heavy users needing more caffeine to produce the same level of alertness as non-users.
Caffeine consumption at levels higher than 300 mg can bring on increased anxiety, states the Coffee Science Information Centre, although caffeine has been shown to decrease anxiety in some people. Caffeine sensitivity varies in individuals, and the exact mechanism of caffeine in the body is unclear. Griffith and Mumford demonstrate that all body tissues absorb caffeine, so it is difficult to isolate caffeine’s effect on tissues, organs and the nervous system.
Chronic caffeine users don’t appear to suffer sleep disturbances. According to Griffith and Mumford, the sleep deprivation effects of caffeine are greater in light coffee drinkers than in heavy coffee drinkers. This could be due to the fact that heavy coffee drinkers require larger doses of caffeine to interrupt their sleep cycles than occasional or light coffee users. Women are more sensitive to caffeine and disturbances in sleep than men are. The half-life of caffeine is roughly 3 to 4 hours, with the exception of pregnant females and women on birth control pills, in which the effects can last up to 12 hours. These groups of women metabolize caffeine at a slower rate than men, so they should avoid caffeinated products to prevent sleep disturbances.
Your central nervous system adapts to repeated exposure to caffeine. In order to produce the same alertness and energy from caffeine, you have to increase the amount you consume. Bodybuilders who use nitrous oxide supplements that include caffeine often experience a euphoric feeling with the first dose that is not repeatable with subsequent doses unless they increase dosage of the supplement or take a break from the caffeine.
Caffeine withdrawal symptoms include headache, agitation and drowsiness, according to Griffith and Mumford. Withdrawal symptoms may be strong enough to make a person go back to using caffeinated beverages to maintain their performance level and avoid the feelings of withdrawal. But symptoms are short lived, lasting only a few days.