Introduction

Definition of shift work sleep disorder 

Shift work sleep disorder (SWSD) is a circadian rhythm sleep disorder characterised by disruptions in an individual's natural sleep-wake cycle due to non-traditional work schedules. This disorder manifests as persistent difficulties in falling or staying asleep when one's work hours conflict with the body's innate (natural) circadian rhythms. Shift workers, including those on night shifts, rotating schedules, or irregular hours, are particularly vulnerable to developing SWSD. The misalignment of work hours with the circadian rhythm can lead to a range of sleep-related issues, and therefore other health problems, making SWSD an important topic, whose research can assist us in understanding and addressing sleep disorders.¹

Importance of addressing shift work sleep disorder

The importance of addressing SWSD cannot be understated. With the increasing demand for non-stop, 24/7 operations in various industries such as healthcare, manufacturing, and transportation, a growing number of individuals are exposed to non-standard work hours. SWSD not only affects an individual's sleep quality but also has broader implications for their overall health, well-being, and, ironically, job performance. Understanding and managing SWSD is crucial in the process of mitigating the negative consequences it can have both on individuals, and the workforce.^2,3

Overview of the article

This article will comprehensively explore SWSD. The structure of the article is organised to guide you through the various aspects of SWSD, ranging from its definition, to the practical strategies that can be used for managing it.

The following sections will discuss the causes of SWSD, including the disruption of circadian rhythms and the impact of irregular work schedules.We will then delve into the symptoms associated with SWSD, detailing how they can affect an individual's sleep quality, daily functioning, and overall health.Furthermore, we will provide insights into the diagnosis of SWSD, highlighting the clinical assessment and tools used to identify the disorder. The article will also present a range of management strategies, ranging from sleep hygiene and light therapy, to medications and behavioural therapies, to help individuals cope with SWSD. A discussion on the importance of open communication with employers and the role of support groups and counselling in addressing SWSD will round out the management section, and, finally, the article will conclude by emphasising the significance of addressing SWSD, encouraging further research and awareness.

Through this structured overview, we aim to set the stage for a comprehensive exploration of SWSD in the subsequent sections of the article.

Definition of shift work sleep disorder

As previously mentioned, SWSD is a circadian rhythm sleep disorder that is characterised by persistent sleep disturbances in individuals whose work hours conflict with their natural circadian rhythms. These disturbances can manifest as difficulties in falling asleep, staying asleep, and experiencing restorative sleep. SWSD primarily affects individuals engaged in shift work, including night shifts, rotating shifts, and irregular work schedules. The disorder is marked by the misalignment between an individual's work schedule andinternal biological clock, leading to sleep-related issues.¹

The circadian rhythm

The circadian rhythm is a fundamental physiological process that regulates various bodily functions, including the sleep-wake cycle, body temperature, hormone production, and metabolism, over a 24-hour period. This internal biological clock is primarily synchronised with the natural light-dark cycle, with the body inclined to be awake and active during the day, and to rest during the night. Disruptions to the circadian rhythm can result in sleep-related disorders, like SWSD. Understanding the role of the circadian rhythm, and how it can be dysregulated, is essential for comprehending how SWSD develops.^4,5

How work schedules disrupt the circadian rhythm

Work schedules that deviate from the traditional 9-to-5 routine can significantly disrupt an individual's circadian rhythm. The primary disruption occurs when individuals are required to work during the night and sleep during the day. Night shifts, in particular, force individuals to stay awake when their biological clock signals a need for sleep. This misalignment can result in sleep disturbances, excessive daytime sleepiness, and other symptoms of SWSD. The irregular work hours, including evening and early morning shifts, contribute to this circadian disruption.6

Variability in shift schedules (day, night, rotating)

SWSD can affect individuals working various shift schedules, including day, night, and rotating shifts. Day shift workers may experience less sleep disturbances due to more regular work hours, and often have more regular sleep patterns when compared to night shift workers. Night shift workers are particularly vulnerable to SWSD as they are required to be awake and active during the body's natural sleep phase. Rotating shift workers, who alternate between day and night shifts, face continuous challenges in adapting to changing schedules, making them susceptible as well to chronic sleep deprivation. Individuals working for long hours may also be more susceptible to developing SWSD.⁷

Impact of rotating shifts

Rotating shifts, where workers alternate between different shifts (e.g., day, evening, night), have a significant impact on the development of SWSD. This type of work schedule disrupts an individual's circadian rhythm and makes it challenging for the body to adapt to a consistent sleep pattern. The constant changes in shift timing can lead to chronic sleep deprivation, contributing to the manifestation of SWSD.⁷

The role of long work hours

Long work hours, especially when combined with non-standard schedules, can exacerbate susceptibility to SWSD and its symptoms.. Extended periods of wakefulness during night shifts can lead to extreme fatigue and sleep disturbances. Prolonged exposure to work hours that extend beyond the typical 8-hour workday can result in sleep deficits, impacting an individual's overall sleep quality.⁸

Environmental factors

The workplace environment itself can significantly contribute to the development and exacerbation of SWSD symptoms. Poor lighting conditions, noisy surroundings, and a lack of exposure to natural light can further disrupt an individual's circadian rhythm. Moreover, the absence of suitable conditions for sleep during daytime hours can hinder the ability to obtain restorative rest.⁹

Diagnosis of shift work sleep disorder

Clinical assessment by healthcare professionals

Clinical assessment by healthcare professionals is a crucial step in diagnosing SWSD. Healthcare providers evaluate a patient's medical history, work schedule, sleep habits, and the presence of specific symptoms. The assessment helps in identifying the presence of SWSD and its severity, while distinguishing it from other sleep disorders.¹⁰

Importance of a sleep diary and actigraphy

Maintaining a sleep diary and using an actigraphy device is essential in the diagnosis of SWSD. A sleep diary records sleep patterns, sleep quality, and daytime symptoms over an extended period, offering valuable insights into the severity of the disorder. Actigraphy on the other hand, involves wearing a device that monitors sleep-wake patterns and can help track sleep disturbances, and this can be particularly helpful in shift workers.¹¹

Clinical criteria for diagnosing shift work sleep disorder 

The diagnosis of SWSD is primarily based on the clinical criteria outlined in the International Classification of Sleep Disorders (ICSD-3). These criteria include the presence of specific symptoms, and evidence of disruption to the circadian rhythm that is caused by shift work. Healthcare providers typically use the criteria found in ICSD-3 to establish a formal diagnosis of SWSD, as it is based on the most recent and well-established research studies.¹

Summary

SWSD is a pervasive challenge for individuals working in industries with non-traditional schedules. This article has delved into SWSD's intricacies, addressing its definition, causes, management, and diagnosis.

The disruptions to circadian rhythms, notably due to rotating shifts and extended work hours, emphasise the urgency of intervention and the adoption of effective management strategies. Quality sleep is intrinsically tied to overall health and well-being, underlining the significance of confronting SWSD.

Employers play a pivotal role in supporting their shift workers by ensuring that work conditions are favourable to their employees, promoting open communication, and implementing policies that prioritise employee health and work-life balance. Behavioural therapies including  cognitive behavioral therapy for insomnia (CBT-I) and light therapy offer promising avenues for managing SWSD symptoms. Seeking professional guidance and participation in support groups can be beneficial to those struggling with this disorder.

In summary, SWSD is a multifaceted sleep disorder with far-reaching consequences. By comprehending its origins, symptoms, diagnostic tools, and deploying effective management techniques, individuals and organisations can collaborate to alleviate its adverse impacts, foster healthier sleep habits, enhance overall well-being, and improve job performance.

References

1. Sateia MJ. International Classification of Sleep Disorders-Third Edition. Chest [Internet]. 2014 Nov;146(5):1387–94. Available from: https://pdfs.semanticscholar.org/3b1f/643e6f9304dca3dffc99b251872c49fcf07d.pdf
2. Drake CL, Roehrs T, Richardson G, Walsh JK, Roth T. Shift Work Sleep Disorder: Prevalence and Consequences Beyond that of Symptomatic Day Workers. Sleep [Internet]. 2004 Dec;27(8):1453–62. Available from: https://academic.oup.com/sleep/article/27/8/1453/2696766
3. Knutsson A. Health disorders of shift workers. Occupational Medicine [Internet]. 2003 Mar 1;53(2):103–8. Available from: https://academic.oup.com/occmed/article/53/2/103/1519795
4. Yalçin M, Mundorf A, Thiel F, Amatriain-Fernández S, Kalthoff IS, Beucke JC, et al. It’s about time: the circadian network as time-keeper for cognitive functioning, locomotor activity and mental health. Front Physiol [Internet]. 2022 Apr 25 [cited 2024 Feb 9];13:873237. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9081535/
5. Brown SS, Azzi A. Peripheral Circadian Oscillators in Mammals. Berlin, Heidelberg: Springer; 2013 [cited 2024 Feb 9]. p. 45–66. (Handbook of Experimental Pharmacology). Available from: https://doi.org/10.1007/978-3-642-25950-0_3
6. Reinberg A, Ashkenazi I. Internal Desynchronization of Circadian Rhythms and Tolerance to Shift Work. Chronobiology International [Internet]. 2008 Jan [cited 2024 Feb 9];25(4):625–43. Available from: http://www.tandfonline.com/doi/full/10.1080/07420520802256101
7. Åkerstedt T, Wright KP. Sleep Loss and Fatigue in Shift Work and Shift Work Disorder. Sleep Medicine Clinics [Internet]. 2009 Jun;4(2):257–71. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904525/
8. CARUSO CC. Possible Broad Impacts of Long Work Hours. Industrial Health. 2006;44(4):531–6. Available from: https://www.jstage.jst.go.jp/article/indhealth/44/4/44_4_531/_article 
9. Patterson PD, Higgins JS, Van Dongen HPA, Buysse DJ, Thackery RW, Kupas DF, et al. Evidence-Based Guidelines for Fatigue Risk Management in Emergency Medical Services. Prehospital emergency care: official journal of the National Association of EMS Physicians and the National Association of State EMS Directors [Internet]. 2018 Feb 15;22(sup1):89–101. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29324069
10. Roth T. Shift Work Disorder. The Journal of Clinical Psychiatry. 2012 Mar 15;73(03):e09. Available from: https://www.psychiatrist.com/jcp/shift-disorder-overview-diagnosis/ 
11. Morgenthaler TI, Lee-Chiong T, Alessi C, Friedman L, Aurora RN, Boehlecke B, et al. Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders. Sleep [Internet]. 2007 Nov 1;30(11):1445–59. Available from: https://academic.oup.com/sleep/article/30/11/1445/2696876

This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Thanvi Buddharaju

Bachelor's degree, Biomedical Engineering, University of Reading

Thanvi Buddharaju is a second-year Biomedical Engineering student at the University of Reading, currently interning with a focus on improving her medical writing skills. Alongside her interest in research, Thanvi navigates the dynamic field of Biomedical Engineering, merging academic pursuits with practical experiences.

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