Methamphetamine attenuates disruptions in performance and mood during simulated night-shift work

Rationale. Increased sleepiness while working and sleep disruptions are common complaints among shift workers. Consequently, shift workers may be more susceptible to diminished performance and work-related accidents. Objective. To examine the effects of the central nervous system stimulant methamphetamine on psychomotor task performance, subjective effects, and food intake during shift work under laboratory conditions. Methods. Seven participants completed this 23-day, within-participant design, residential laboratory study. They received a single oral methamphetamine dose (0, 5, 10 mg) 1 h after waking for three consecutive days under two shift conditions: (1) during the day shift, participants performed computerized psychomotor tasks from 0830 hours to 1730 hours and went to bed at 2400 hours and (2) during the night shift, participants performed tasks from 0030 hours to 0930 hours and went to bed at 1600 hours. Shifts alternated three times during the study; shift conditions were separated by an off day during which participants were not on a schedule and data were not collected. Results. When participants received placebo, psychomotor task performance and subjective effects were disrupted during the night shift, relative to the day shift. Changing shift conditions did not alter food intake significantly. Methamphetamine reversed performance and subjective-effects disruptions, and decreased food intake during the night shift. Conclusion. These data indicate that shift changes produce performance impairments and mood alterations, and that a single low to moderate dose of methamphetamine attenuates many shift change-related disruptions in performance and mood.