Shift work: health, performance and safety problems, traditional countermeasures, and innovative management strategies to reduce circadian misalignment

Abstract

There are three mechanisms that may contribute to the health, performance, and safety problems associated with night-shift work: (1) circadian misalignment between the internal circadian clock and activities such as work, sleep, and eating, (2) chronic, partial sleep deprivation, and (3) melatonin suppression by light at night. The typical countermeasures, such as caffeine, naps, and melatonin (for its sleep-promoting effect), along with education about sleep and circadian rhythms, are the components of most fatigue risk-management plans. We contend that these, while better than nothing, are not enough because they do not address the underlying cause of the problems, which is circadian misalignment. We explain how to reset (phase-shift) the circadian clock to partially align with the night-work, day-sleep schedule, and thus reduce circadian misalignment while preserving sleep and functioning on days off. This involves controlling light and dark using outdoor light exposure, sunglasses, sleep in the dark, and a little bright light during night work. We present a diagram of a sleep-and-light schedule to reduce circadian misalignment in permanent night work, or a rotation between evenings and nights, and give practical advice on how to implement this type of plan.

Keywords:

• circadian rhythms
• night work
• bright light
• phase-shifting
• sleep
• melatonin

Acknowledgments

The studies referred to in this review as ours were performed in the Biological Rhythms Research Laboratory of Rush University Medical Center in Chicago, and were primarily supported by grant R01OH003954 from the National Institute of Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC) and also by grants from the National Institutes of Health (R01NS23421, R01NS35695, R01NR07677, R01HL086934) to Charmane Eastman. The content is solely the responsibility of the authors and does not necessarily represent the official views of the granting institutions: the National Institute of Occupational Safety and Health and the National Institutes of Health. These institutes had no involvement in designing the studies, data collection, data analysis and interpretation, or the writing of this manuscript. The authors have no conflicts of interest and did not receive any funds or salary support for writing this manuscript. We thank Daniel L Johnson, MD, for plodding through an earlier draft and providing tips for writing science for a lay audience.

Disclosure

The authors report no conflicts of interest in this work.