Psychophysiological Effects of Extended Workshifts

Abstract

Working extended workshifts has been linked to decrements in behavioral performance and physiological function, plus subjective complaints. This report describes findings before and after workers in an underground mine converted from a continuous 8-hour to a 12-hour rotating shift schedule. A psychophysiological approach to work schedule evaluation was employed, involving continuous heart rate (HR) recording accompanied by pre-, mid-, and post-shift measures of cognitive and psychomotor behavioral performance, HR recovery and estimated VO_2max levels using submaximal exercise testing, and subjective mood and sleepiness responses. The continuous HR results suggest adaptation of work effort or output on 12-h relative to 8-h shifts. Some measures of performance, namely self-report mood and sleepiness responses plus HR recovery, suggest more fatigue on 12-h shifts. We conclude that working extended workshifts may result in an adaptive response to fatigue, manifest in the form of pacing or modulated work effort by the workforce.