Positive Stimulant Effects of Caffeine Caffeine is a mild stimulant, acting on the central nervous system and some other organs of the body, for example the kidneys. It also increases metabolic rate. Consumption of caffeine equivalent to that found in a couple of cups of coffee has been shown to improve alertness and enhance concentration. Alertness and Mood o Caffeine can increase the speed of rapid information processing by 10% o A cup of regular (caffeine-containing) coffee after lunch helps to counteract the normal 'post-lunch dip' in ability to sustain concentration, aiding alertness o Improve alertness and concentration during night shift hours Conducted a study in 1993 to examine the effects of coffee on daytime and night-time performance and alertness. The results clearly demonstrated that caffeinated coffee had a beneficial effect on alertness and improved performance in a variety of tasks in both day and night sessions. These effects are especially beneficial to night shift workers as it is known that many industrial accidents occur late into the shift when workers become less attentive.

o Remove the malaise (reduced alertness, slower psychomotor performance) associated with having the common cold, and that increased stimulation of the sensory afferent nerves may also be beneficial. o Improve performance independently of its raising of fatigue-related concentration o Increased self-reported vigor, alertness and efficiency, and a decline in levels of depression and anxiety. Stimulants work by mimicking the fight-or-flight response, in which the hormone epinephrine (also known as adrenaline), is released during stressful situations to produce an increased heart rate and increased blood flow to the muscles. Stimulants produce a similar, but often more powerful, response by increasing levels of the neurotransmitters dopamine and norepinephrine in the brain. Physical Performance o Improve athletic performance, for example in swimming (10) cycling (11) and women's tennis. Analysis of data from the UK Health and Lifestyle Survey found that, for coffee drinkers especially, caffeine-related improvements in performance do not decline with regular consumption.

Rather than developing tolerance to these effects, habitual coffee drinkers continue to perform better in a variety of cognitive performance tests, compared with non-consumers (13).