Shiftwork and Sleep Disruption: A Dangerous Combination

Shiftwork and Sleep Disruption: A Dangerous Combination

Shift workers are more vulnerable for which of the following disorders?

1. Metabolic syndrome
2. Mood disorders
3. Heart disease
4. Cancer
5. All of the above

Answer: All of the above.

Among the 21 million Americans engaged in shiftwork, approximately 10% develop signs and symptoms of impairment associated with this work schedule, primarily insomnia and daytime sleepiness. Shiftwork involves a recurrent pattern of working during hours that overlap the usual time for sleep.  When daytime sleepiness and insomnia develop as a result of this pattern and these symptoms last a month or longer, shiftwork disorder (SWD) may have developed. 

Data indicate that shift workers are vulnerable to the development of all the medical and psychiatric abnormalities listed here, and that some are more likely to occur in the context of SWD.  The mechanisms behind these associations are still a matter of research. 

Individuals with SWD are also vulnerable to impairments that result from daytime sleepiness, including decrements in job performance, somnolence while working, and impaired ability to drive.

Questions regarding shiftwork should be included in the workup of all individuals who present with complaints of insomnia or excessive daytime sleepiness. Sleep logs or diaries that patients complete over the course of a few weeks can be very helpful in understanding the pattern of sleep and work across time. A highly useful inventory is the Epworth Sleepiness Scale which quantifies the extent of sleepiness; it is easily completed by patients in less than a minute. A score above 10 is abnormal and warrants further evaluation

Take-home points:
1. Shift work can lead to significant impairments in health and well-being
2. In patients complaining of insomnia or excessive daytime sleepiness, ask about shift work

Suggested reading:
• Barger LK, Lockely SW, et al, for the Harvard Work Hours, Health and Safety Group. Sleep disorders, health, and safety in police officers. JAMA. 2011;306:2567-2578.

• Drake CL, Roehrs T, Richardson G, Walsh JK, Roth T.  Shift work sleep disorder: prevalence and consequences beyond that of symptomatic day workers. Sleep. 2004;27:1453-1462.
• International Classification of Sleep Disorders Diagnostic and Coding Manual. 2nd ed. Westchester, IL: American Academy of Sleep Medicine; 2005.

• Straif K, Baan R, Grosse Y, et al. Carcinogenicity of shift-work, painting, and fire-fighting. Lancet Oncol. 2007;8:1065-1066.

• Culpepper L. The social and economic burden of shift-work disorder. J Fam Pract. 2010;59:(  Suppl):S3-S11.


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