Effect of Caffeine on Vigilance and Cognitive Performance During Extended Wakefulness

In this double-blind, randomized, 37-hr sleep deprivation study, 15 military pilot students received either placebo or 200 mg of caffeine twice a day. Vigilance was assessed 6 times and learning 4 times, both in a computerized environment. Motivation, mood, and sleepiness were monitored using self-ratings. In the vigilance test, sleep deprivation decreased the amount of correct detections and increased reaction times in both groups. Furthermore, the number of false alarms increased in the placebo group. Participants receiving caffeine showed overconfidence, as they did not report any clear decline in subjectively assessed success despite impaired performance in the vigilance test.