Shift work and the assessment and management of shift work disorder (SWD)

Available online 2 May 2012

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a Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado at Boulder, 1725 Pleasant Street, Boulder, CO 80309, USAb SleepMed Incorporated, SleepMed of South Carolina, 700 Gervais Street, Suite #200, Columbia, SC 29201, USAc School of Medicine, University of South Carolina, USAd Sleep Disorders Service and Research Center, Rush University Medical Center, Johnston R. Bowman Health Center, 710 S. Paulina Street, 6 South JRB, Chicago, IL 60612, USAReceived 5 July 2011. Revised 10 February 2012. Accepted 13 February 2012. Available online 2 May 2012.View full text Nearly 20% of the labor force worldwide, work shifts that include work hours outside 07:00 h to 18:00 h. Shift work is common in many occupations that directly affect the health and safety of others (e.g., protective services, transportation, healthcare), whereas quality of life, health, and safety during shift work and the commute home can affect workers in any field.

Increasing evidence indicates that shift-work schedules negatively influence worker physiology, health, and safety. Shift work disrupts circadian sleep and alerting cycles, resulting in disturbed daytime sleep and excessive sleepiness during the work shift. Moreover, shift workers are at risk for shift work disorder (SWD). This review focuses on shift work and the assessment and management of sleepiness and sleep disruption associated with shift work schedules and SWD. Management strategies include approaches to promote sleep, wakefulness, and adaptation of the circadian clock to the imposed work schedule. Additional studies are needed to further our understanding of the mechanisms underlying the health risks of shift work, understanding which shift workers are at most risk of SWD, to investigate treatment options that address the health and safety burdens associated with shift work and SWD, and to further develop and assess the comparative effectiveness of countermeasures and treatment options.

prs.rt("abs_end");Shift work; Shift work disorder; Circadian rhythm; Circadian adaptation; Circadian misalignment; Homeostatic sleep drive; Good sleep behavior; Sleep duration; Caffeine; Naps; Melatonin; Hypnotics; Armodafinil; Modafinil

Figures and tables from this article:

Fig. 1. Occupations with a large proportion of shift workers (>20%).8

View Within ArticleFig. 2. Characterization of brain arousal across the 24-h day in a typical day worker and a night shift worker. Wakefulness and sleep are dependent upon the interplay between the circadian alerting signal and the homeostatic sleep drive in day- and night-shift workers. In a typical day worker (A), the sleep and circadian systems interact in such a way that alert wakefulness is promoted during the day and sleep is promoted at night. A circadian arousal signal increases across the day to counteract the buildup of sleep pressure that occurs with time awake. In a non-adapted night-shift worker (B), the circadian arousal signal increases across the day when the shift worker is attempting to sleep, resulting in short sleep duration. During the night shift, the circadian system and sleep pressure promote sleep, leading to excessive sleepiness during the work shift. Modified from Drake, 2010.128

View Within ArticleFig. 3. Baseline untreated. In the modafinil study (n = 182) (data on file)69 and armodafinil study (n = 216) (data on file, Cephalon),70 mean nighttime sleep latencies at baseline in untreated patients with shift work disorder (SWD) decreased over the course of a laboratory night shift. Sleep latency data from healthy control groups in three relatively small (n = 15–30), simulated, night-shift studies are also depicted (Study 1: Walsh et al., 1988; Study 2: Walsh et al., 1991; Study 3: Muehlbach and Walsh, 1995 [74], [75] and [76]) showing that healthy controls are more alert than patients with shift work disorder (A). A worsening of subjective sleepiness, as measured by the Karolinska sleepiness scale (KSS), also was seen in the modafinil and armodafinil studies in patients with SWD (B). Modafinil study: At the final visit of the modafinil study (n = 182), multiple sleep latency test (MSLT) scores for the modafinil group had significantly improved from baseline, compared with MSLT scores for the placebo group, at 02:00 h and 04:00 h but not at 06:00 h or 08:00 h (C). KSS scores in the modafinil group were also significantly improved at each time point from midnight to 05:00 h and also at 07:00 h, compared with scores in the placebo group (D).69 Panel C adapted with permission from Czeisler et al., 2005.69 Armodafinil study: At the final visit of the armodafinil study (n = 216), MSLT scores for the armodafinil group were significantly improved, compared with MSLT scores for the placebo group, at all time points measured (E). KSS scores also were significantly improved at each time point from 23:55 h to 05:55 h in the armodafinil group (F).70 Panels E and F reprinted with permission from Czeisler et al., 2009.70*p < 0.001; †p < 0.05, change from baseline vs. placebo. Higher KSS scores indicate greater sleepiness.

View Within ArticleTable 1. Diagnostic and supportive criteria for shift work disorder.13

View Within ArticleTable 2. Clinical guidelines for assessment and management of shift work disorder (SWD).73

ESS, Epworth sleepiness scale; SWD, shift work disorder; KSS, Karolinska sleepiness scale. Modified with permission from Drake and Wright.73

View Within ArticleCopyright © 2012 Elsevier Ltd. All rights reserved.

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