Coffee is great, and coffee connosieurs (and addicts?) can attest to that. But what do the experts say about the effects of caffeine?
Caffeine is a mild stimulant of the central nervous system and as a result can influence human behaviour. This includes effects on aspects of mood such as alertness and anxiety, mental performance and sleep. Studies of effects of caffeine on human behaviour often use very high intakes and the relevance of the results of these studies to normal levels of caffeine consumption are questionable. In addition, such studies often look at the effects of a single dose of caffeine and the relevance of this to long-term caffeine consumption can also be questioned as the body may well adapt over the long-term. It is also clear that there is considerable individual variation in the response of human behaviour to caffeine ingestion and extrapolation of the results from a small study population to the general population is likely to produce spurious results.