Effects of circadian misalignment on cognition in chronic shift workers

Christopher J Morris,Frank A J L Scheer,Sarah L Chellappa

doi:10.1038/s41598-018-36762-w

Christopher J Morris, Frank A J L Scheer + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-36762-w

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Abstract

Shift work is associated with increased human operational errors, presumably due to the circadian timing system that inhibits optimal cognitive function during the night. Circadian misalignment, which is the misalignment between the circadian pacemaker and behavioral/environmental cycles, impairs cognitive performance in non-shift workers. However, it remains uncertain whether the adverse cognitive consequences of circadian misalignment are also observed in chronic shift workers. Thus, we investigated the effects of circadian misalignment on cognitive performance in chronic shift workers. Using a randomized, cross-over design that simulated day shift work (circadian alignment) and night shift work (circadian misalignment), we show that circadian misalignment increases cognitive vulnerability on sustained attention, information processing and visual-motor performance, particularly after more than 10 hours of scheduled wakefulness. Furthermore, their increased levels of subjective sleepiness and their decreased sleep efficiency were significantly associated with impaired sustained attention and visual-motor performance. Our data suggest that circadian misalignment dramatically deteriorates cognitive performance in chronic shift workers under circadian misalignment. This increased cognitive vulnerability may have important safety consequences, given the increasing number of nighttime jobs that crucially rely on the availability of cognitive resources.

Highlights

Shift work is typically referred to as an employment practice design to cover the 24-h day and night needed for duty performance in contemporary society[1,2], and 14% of Americans perform their work during the night[3]
Our data indicate deteriorated performance in tasks associated with sustained attention, information processing and visual-motor performance in chronic night shift workers under circadian misalignment, after 11 hours of scheduled wakefulness
These data suggest that when chronic shift workers are under circadian misalignment their performance may dramatically deteriorate if exposed to longer durations of wakefulness

Summary

Introduction

Shift work is typically referred to as an employment practice design to cover the 24-h day and night needed for duty performance in contemporary society[1,2], and 14% of Americans perform their work during the night[3]. Circadian misalignment impairs cognitive performance, as indexed by sustained attention, cognitive throughput, information processing and visual-motor performance, in chronic shift workers.

Results

Conclusion