What are the short term effects of caffeine on the body?
Caffeine increases heartbeat, respiration, basal metabolic rate, gastroenteric reflexes, and the production of stomach acid and urine; and it relaxes smooth muscles, notably the bronchial muscle. All of these changes vary considerably among people and may depend upon the individual’s sensitivity to this drug, his/her metabolism, or upon whether the consumer habitually uses or rarely uses caffeine. How long caffeine’s effects last is influenced by the person’s hormonal status, whether he/she smokes or takes medications, or has a disease that impairs liver functioning. Subjectively, people report that caffeine gives them a “lift.” They feel less drowsy, less fatigued, more capable of rapid and sustained intellectual effort. They also report improved performance of some manual tasks such as driving. However, caffeine may restore only those abilities or feelings the person had before fatigue or boredom set in. Studies have also shown that caffeine decreases reaction time to both visual and
