Effects of High Habitual Caffeine Use on Performance During One Night of Sleep Deprivation: Do High Users Need Larger Doses to Maintain Vigilance?

Abstract

Background: Caffeine is the most widely used stimulant for maintaining alertness and countering the effects of sleep loss. Ninety percent of adults in the United States consume caffeine daily with some ingesting more than 400 mg/day. This raises the question of whether caffeine maintains effectiveness in high habitual users. Methods: Sixteen participants, 18–35 years of age, volunteered. Eight were low caffeine users and eight were high users. Each subject completed four separate trials (100, 200, or 300 mg caffeine or placebo). A multidose crossover paradigm was used during one night without sleep. Participants received doses in a chewing gum formulation at the beginning of each 2-hour test block. Results: There was no difference in performance at 100, 200, or 300 mg of caffeine between high and low users. High users performed faster than low users with placebo. Within-group analyses revealed that 100 mg of caffeine was unable to sustain performance compared to baseline in high users, while it was sufficient in low users. There were also differences in responsiveness within user groups. Conclusions: High users of caffeine do not appear to need more caffeine compared to low users to maintain performance. However, larger doses may be more sufficient at sustaining baseline performance compared to smaller doses in high users.