Abstract

Andrew P. Smith PhD*

ABSTRACT

Background: Most research on caffeine has given it in beverages or capsules. Recently, caffeinated chewing gum has been produced and this leads to very rapid absorption and positive behavioural effects with a dose of 40mg. Caffeine often has its greatest benefit in low alertness states, and the present study examined this topic using caffeine in chewing gum. Methods: Volunteers (N=48) were randomly assigned to caffeinated gum, placebo gum or no gum conditions. Half of each group were sleep deprived and tested between 04.00 and 07.00, whereas the others were allowed normal sleep before testing between 09.00 and 12.00. Baseline measures of mood and performance were taken before chewing the gum. The gum was then chewed before repeating the tasks. Results: The results showed few differences between the placebo gum and no gum conditions and these groups were combined to form the control group. The results showed that caffeinated gum increased ratings of alertness and hedonic tone but not anxiety. The caffeinated gum group showed improved performance on the simple reaction time task, detection of repeated numbers task and five-choice serial response task. There were no significant effects of caffeine on the memory tasks. Conclusion: The results showed the profile of effects that one would expect from the caffeine literature. The changes seen after caffeine were not modified by level of fatigue induced by sleep deprivation. The magnitude of the caffeine effects were in the region of about half a standard deviation which is consistent with the size of effects seen in other studies, and are of a magnitude that may be of practical importance in real-life activities.