The influence of irregularity of rest and activity on performance: a model based on time since sleep and time of day

Abstract

Changes in performance during a 9 day period of an irregular schedule of work and rest were investigated. Performance varied with the circadian rhythm and the length of the work periods. For the majority of subjects these two factors were additive. The time-of-day variation was well approximated by a sinusoid and the time-since-sleep factor was represented by a cubic trend. The acrophase of the circadian rhythm varied throughout the experiment under the influence of the sleep-wake cycle and the time-of-day cues. A model which included time of day and time since sleep was used to predict variations in performance for work periods starting at different times of the day. It is considered that this model can be applied to current issues in the scheduling of civil airline pilots’ duty periods.

Keywords:

• Circadian rhythms
• Mathematical models
• Irregular schedules
• Performance
• Body temperature rhythm