ABSTRACT
RATIONALE: There is a vast literature on the behavioural effects of caffeine. Many of the studies have involved single administration of a large dose of caffeine that is not representative of the way in which caffeine is usually ingested. Further information is required, therefore, on the behavioural effects of realistic patterns of consumption. OBJECTIVES: The present study aimed to determine whether a realistic drinking regime (multiple small doses - 4 x 65 mg over a 5-h period) produced the same effects as a single large dose (200 mg). The smaller doses were selected so that the amount of caffeine present in the body after 5 h would be equivalent to that found with the single dose. METHODS: A double-blind, placebo-controlled, within-subjects experiment was, therefore, carried out. The participants ( n=24) attended for four sessions. Each session started with a baseline measurement of mood and performance at 0930 hours. On two of the sessions, coffee was then consumed at 1000, 1100, 1200 and 1300 hours. In one of these sessions 65 mg caffeine was added to the de-caffeinated coffee. In the other two sessions, the participants consumed coffee at 1300 hours and 200 mg caffeine was added in one of the sessions. The volunteers completed the battery of tests again at 1500 hours. RESULTS: The results showed that in both consumption regimes caffeine led to increased alertness and anxiety and improved performance on simple and choice reactive tasks, a cognitive vigilance task, a task requiring sustained response and a dual task involving tracking and target detection. CONCLUSIONS: These results suggest that previous findings from studies using a large single dose may be applicable to normal patterns of caffeine consumption.
Subject(s)
Affect/drug effects , Attention/drug effects , Caffeine/pharmacology , Central Nervous System Stimulants/pharmacology , Psychomotor Performance/drug effects , Adult , Coffee/chemistry , Dose-Response Relationship, Drug , Double-Blind Method , Drug Administration Schedule , Humans , Male , Reaction Time/drug effects , Saliva/chemistryABSTRACT
The main aim of this research was to identify factors that were related to caffeine consumption. From this investigation it can be concluded that coffee is the main source of caffeine and that consumption varies with time of day. Individuals may be utilising the arousing effects of caffeine by consuming it at times when arousal is low for instance to counteract sleep inertia or a post-lunch dip in alertness. There is, however, very little evidence to suggest that psychological characteristics such as personality traits or psychosocial factors are important in influencing caffeine consumption, although smoking was found to be related to the amount of caffeine consumed.
