Understanding Shift Work Sleep Disorder (SWSD): Causes, Diagnosis, and Prevention

Source: Moreno, C. R. C. (2025). Shift work sleep disorder. In Handbook of Clinical Neurology (Vol. 206, pp. 89–92). Elsevier. https://doi.org/10.1016/B978-0-323-90918-1.00015-0

Why This Topic Matters

As a nurse and author who has spent years working rotating night shifts, I’ve seen firsthand how circadian disruption impacts alertness, performance, and long-term health. Shift work sleep disorder (SWSD) isn’t simply “bad sleep.” It’s a recognized circadian rhythm disorder that arises when work hours clash with the body’s biological clock — the same system that regulates hormone release, body temperature, and cognitive function.

What Is Shift Work?

According to the International Labour Organization (ILO), shift work is “a method of organizing working time in which workers succeed one another at the workplace so that operations can continue beyond the working hours of individual employees.”This structure keeps essential services like healthcare, transportation, and emergency response running 24/7 — but often at the cost of workers’ biological stability.

Since the 1980s, labor shortages, globalization, and extended service demands have expanded shift work across industries. The result: growing exposure to fatigue-related illness, metabolic dysfunction, and cognitive decline among night and rotating-shift workers.

What Is Shift Work Sleep Disorder (SWSD)?

The ICD-11 defines SWSD as a circadian rhythm sleep–wake disorder, shift work type (code: 7A64).The International Classification of Sleep Disorders, Third Edition (ICSD-3-TR) also formally recognizes SWSD as a distinct diagnosis.

Key Symptoms

• Difficulty sleeping during the day after night shifts

• Excessive sleepiness and microsleeps during work hours

• Impaired alertness leading to errors or accidents

• Long-term risk of cardiovascular disease, diabetes, obesity, depression, and certain cancers

Only about 30% of night and rotating shift workers meet diagnostic criteria for SWSD — but those affected face significant health and occupational risks.

Diagnosing SWSD

Diagnosis requires a combination of clinical evaluation and objective sleep monitoring:

• Sleep diaries or actigraphy: Track sleep duration and quality over multiple weeks.

• Polysomnography: Rule out other disorders such as sleep apnea or restless legs syndrome.

• Schedule analysis: Compare reported symptoms with shift rotations and light exposure patterns.

Accurate diagnosis often requires the input of sleep specialists, occupational health providers, and primary care clinicians.

Evidence-Based Treatment and Prevention

While returning to daytime work remains the most effective solution, it’s often impractical. Instead, a dual approach — workplace-level and individual-level interventions — provides the best outcomes.

Workplace-Level Strategies

• Design forward-rotating schedules and shorter night shifts

• Implement fatigue risk management systems

• Provide nap-friendly environments and safe commuting policies

Individual-Level Strategies

• Sleep hygiene: Create a dark, cool, and quiet environment using blackout curtains, eye masks, and white noise

• Light therapy: Use bright light exposure at shift onset; block morning light on the commute home

• Melatonin supplementation: Adjust timing to facilitate daytime sleep

• Pharmacologic support: Under medical supervision, agents such as modafinil or armodafinil may help sustain wakefulness

Professional Insight

As a clinician and shift worker, I’ve witnessed how biological misalignment manifests not only in fatigue but also in mood changes, immune dysfunction, and decision fatigue. Sleep optimization isn’t just a personal habit — it’s an occupational safety strategy.

Final Takeaway

Shift work sleep disorder is preventable and manageable with awareness and early intervention. When employers prioritize fatigue mitigation and workers adopt evidence-based sleep strategies, both productivity and health outcomes improve.

By aligning medical research with real-world experience, we can build a healthier, more sustainable 24-hour workforce — one that recognizes rest as essential, not optional.

Author: R.E. Hengsterman, MSN, MA, M.E., RN

Registered nurse, night-shift administrator, and author of The Shift Worker’s Paradox

Nursewhowrites.com

For educational purposes only. Not medical advice.