Caffeine, but not time of day, increases whole-arm physiological tremor in non-smoking moderate users

1. Consumptive levels of caffeine significantly increased whole-arm physiological tremor in young adult males at 3 but not 1 mg caffeine/kg bodyweight. 2. Physiological tremor was not affected by time of day (TOD) or the interaction of caffeine and TOD, 3, Findings suggest that ingestion of a single oral dose of caffeine at typical consumptive levels results in measurable changes in physiological functioning and that whole-arm physiological tremor is a sensitive measure of physiological change due to drug effects, 4. However, the results suggest that whole-arm physiological tremor may not detect reliably TOD changes in functioning.