Investigating the relative effects of sleep deprivation and time of day on fatigue and performance

▶ Circadian influences only affected the performance in combination with long wakefulness. ▶ Rested people showed good performance even during the circadian trough. ▶ Work in midnight to dawn period may not involve higher risk of performance deficits. ▶ Long work hours that extend into the circadian trough period should be avoided.