SUPPRESSION OF SLEEPINESS IN DRIVERS - COMBINATION OF CAFFEINE WITH ASHORT NAP

Previous research has shown that caffeine and a <15-min nap effectivel y and separately reduce sleepiness in drivers for 1 hr. In the present study, we examined in 12 sleepy individuals the treatments combined, taken during a 30-min break, prior to a longer (2 hr) continuous monot onous afternoon drive in a car simulator. Nonnap comparisons were 200 mg caffeine only and placebo. For placebo, driving incidents, subjecti ve and electroencephalographic measures of sleepiness all reflected a mid-afternoon peak. This peak was significantly reduced by caffeine an d eliminated by the combined treatment, which reduced incidents to 9% of placebo levels versus 34% of placebo levels for caffeine alone. Nap s comprising ''nonsleep dozing'' were still effective.