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Shiftwork and Mental Health

The evidence regarding shiftwork and mental health is incomplete. While some studies did not find any differences between shiftworkers and day workers (Cole et al. 1990), others have found that shiftwork is related to poor mental health (Eskelinen et al. 1991, Estryn-Behar et al. 1990, Kandolin 1993).

Fischer et al. (2001) found that shiftwork was a significant risk factor for depression. Costa et al. (1981) showed that the prevalence of neurotic disorders was higher among rotating three-shift workers and permanent night workers compared to dayworkers.

Although there is some evidence pointing to a relationship between shiftwork and poor mental health, there is not a clear understanding of which factors could be responsible.
Several mechanisms have been suggested, mainly desynchronization of circadian rhythms and increased stress, related to conflicts between work and family and social activities.

Additionally, disturbances of the circadian rhythms, such as phase-advance of circadian rhythms and internal desynchronization, have been suggested as causal factors in depressive illness. Moreover, Seasonal Affective Disorder (SAD) has been related to disturbed circadian rhythms (in this case, phase-delay) and the treatment with bright light exposure, readjusting the rhythms, results in improved mood.

On the other hand, the fact that disturbed circadian rhythms have been found in depressed patients raises the question of whether disruption of circadian rhythms by external causes, such as shiftwork, can induce or exacerbate depression. It has been suggested that some complaints of depression among shiftworkers may be the consequence of their disrupted circadian rhythms and/or lower exposure to daylight (Costa 1997).

Exacerbating any mental health risk factors is the fact that Circadian’s data and other research shows that workers in extended hours operations have a higher frequency of unhealthy lifestyle behaviors.  

  • Circadian’s research indicates that alcohol drinking is much more prevalent among extended hours workers than for the average population (Aguirre 2003).
  • Fifty-four percent of extended hours workers smoke or reported a history of smoking (Aguirre 2003), compared to the approximately 19.8% of U.S. adults that are current cigarette smokers (CDC 2008). 
  • Caffeine use has been found to be higher among workers in extended hours operations than among day workers (Aguirre et al. 1994). 
  •  The majority of extended hours workers do not exercise regularly (77%), compared to 55% of the general population (Aguirre 2003), (Gallup 2003). 
  • Only about one quarter of extended hours workers (28%) reported having good nutritional practices as compared to one third of the average population (Berrigan et al. 2003). 
  • Moreover, Circadian’s data showed there is a relationship between lifestyle behaviors, and individuals tend to have several good or poor habits (i.e., those who smoke tend to drink more alcohol, have poor nutrition and exercise less).

How Can Shiftworker Wellness be Improved?

“Commitment to shiftwork” has been cited by several researchers as the most important individual factor affecting shiftwork tolerance and wellness. Commitment to shiftwork means that shiftworkers are willing to schedule their lives around working non-traditional hours. Correct sleeping habits, appropriate exposure to bright light, good nutritional practices, and physical exercise may all have a crucial effect on shiftwork tolerance (Rosa et al. 1990).

While you cannot supervise each individual shiftworker to make sure they are committed to a shiftwork lifestyle, you can put them in a situation to succeed. This means providing them with training and educational materials that inform them of positive steps they can take to adjust to shiftwork and improve their mental and physical health.

For example, many shiftworkers report increased stress related to conflicts between work and family and social activities. By providing information on how to deal with the family and social challenges of shiftwork, you can help alleviate the stress in their lives. For instance, one study found that shiftworkers with good family lives reported better health status (Taylor et al. 1997).

Likewise many shiftworkers have trouble getting quality sleep while working the night shift. As most people know from personal experience, sleep deprivation can worsen your mood and cause your productivity to suffer. By educating shiftworkers on how to improve daytime sleep and improve alertness, you can help improve their mental and physical health.


Aguirre A. Health In Extended Hours Operations: Understanding the Challenges, Implementing the Solutions. Circadian Technologies, Inc. 2003.

Cole RJ, Loving RT, Kripke DF. Psychiatric effects of shiftwork. In: Occupational Medicine: State of the Art Reviews 5(2), 301-314. 1990.

Eskelinen L, Toikkanen J et al. Symptoms of mental and physical stress in different categories of municipal work. Scand. J. Work Environ. Health 1 (Suppl.), 82-86. 1991.

Estryn-Behar M, Kaminski M et al. Stress at work and mental health status among female hospital workers. Br. J. Ind. Med. 4, 20-28. 1990.

Kandolin I. Burnout of female and male nurses in shift work. Ergonomics 36, 141-147. 1993.

Fischer FM, Morata TC, Latorre MR, et al. Effects of environmental and organizational factors on the health of shiftworkers of a printing company. J. Occup. Environ. Med. 43, 882-889. 2001.

Costa G, Apostoli P, D’Andrea F, Gaffuri E. Gastrointestinal and neurotic disorders in textile shift workers. In: Night and shift work: biological and social aspects. A Reinberg, N Vieux, P Andlauer (eds.). Pergamon Press, Oxford. 1981.

Costa G. The problem: shiftwork. Chronobiol. Int. 14(2), 89-98. 1997.

Berrigan D, Dodd K, Troiano RP, Krebs-Smith SM, Ballard Barbash R. Patterns of health behavior in US adults. Preventive Medicine 36, 615-623. 2003.

Centers for Disease Control and Prevention. Cigarette Smoking Among Adults—United States, 2007. Morbidity and Mortality Weekly Report [serial online]. 2008;57(45):1221–1226 [accessed 2009 Mar 31].

Gallup Poll Social Series. Health and healthcare. The Gallup Organization, Princeton. 2003.

Aguirre A, and Foret J. Irregularity of working hours in railway workers and types of complaints. International Archives of Occupational and Environmental Health 65, 367-371. 1994.

Rosa RR, et al. Intervention factors for promoting adjustment to nightwork and shiftwork. Occupational Medicine: State of the Art Reviews 5 (2), 391-415. 1990.

Taylor E, et al. Shiftwork advantages as predictors of health. International Journal of Occupational and Environmental Health 3 (2):S20-S29. 1997.

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