Abstract

EFFECTS OF CAFFEINE IN TEA AND HOT WATER ON ALERTNESS, SIMPLE REACTION TIME AND ATTENTION

Andrew P. Smith*, PhD

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Abstract

Background: Coffee and tea are major sources of caffeine and have often been used as the vehicle in which caffeine has been delivered in laboratory research. Instant coffee has been frequently used, but there are few studies on the behavioral effects of instant tea. There has been a great deal of research on the behavioural effects of caffeine, and sensitive tests have been identified. The present study compared the effects of tea and hot water, with and without caffeine added. Methods: Ninety-six university students participated in the research. There were twenty-four in each of the four groups formed by combining caffeine/placebo and tea/hot water conditions. The caffeine condition was double-blind, and 60mg of caffeine was added to the caffeine conditions. Instant tea, with added milk, was compared with hot water. Participants carried out a baseline test session, followed by drinks, and then a post-drink test session one hour later. The test battery included measures of alertness, simple reaction time, choice reaction time, sustained attention, episodic memory, working memory and semantic memory. Results: Significant beneficial effects of caffeine were observed for changes in alertness, simple reaction time and sustained attention. There were no significant main effects of tea nor caffeine x tea interactions. Conclusion: Caffeine was found to lead to the usual established behavioural changes. This was observed whether it was given in tea or hot water. There was no evidence of significant effects of drink type (tea v hot water), and the effects of caffeine were apparent in both types of drink.

Keywords: Tea, Caffeine, Alertness, Simple reaction time, Sustained attention.