Diagnostic Criteria for Shift Work Sleep Disorder
Shift work disorder (SWD) is diagnosed when a patient experiences excessive sleepiness during work hours or insomnia during daytime sleep periods, temporally associated with a work schedule that overlaps the habitual sleep phase, with symptoms present for at least 3 months and documented by sleep diaries or actigraphy for at least 7 days. 1, 2
Core Diagnostic Criteria
The diagnosis requires all of the following components:
Primary complaint of excessive sleepiness or insomnia that is temporally associated with a work period (usually night work) occurring during the habitual sleep phase 1
Duration requirement: Symptoms must be present for at least 3 months 1
Objective documentation: Sleep-wake patterns must be documented with sleep diaries and/or wrist actigraphy for a minimum of 7 days 3, 1
Exclusion criteria: No other medical or mental disorder accounts for the symptoms, and symptoms do not meet criteria for any other sleep disorder producing insomnia or excessive sleepiness 1
Key Diagnostic Features
Temporal Association with Work Schedule
The sleep disturbance must be directly linked to a recurring work schedule that overlaps the usual time designated for sleeping 4
Polysomnography and Multiple Sleep Latency Test (MSLT) may demonstrate loss of normal sleep-wake pattern (disturbed chronobiological rhythmicity) 1
Severity Thresholds for Clinical Trials
When SWD was studied in clinical trials, patients were required to meet these additional criteria:
- Excessive sleepiness: MSLT score < 6 minutes during night shifts 1
- Daytime insomnia: Documented by daytime polysomnogram 1
- Minimum work requirement: At least 5 night shifts per month 1
- Baseline sleepiness: Epworth Sleepiness Scale (ESS) score ≥10 1
Critical Diagnostic Pitfall
Not all shift workers with sleepiness complaints meet diagnostic criteria for SWD 1. The disorder requires clinically significant disturbances in sleep, fatigue, and/or circadian alignment that cannot be attributed to other causes 3. Many shift workers experience sleep difficulties without meeting the full diagnostic threshold for SWD.
Objective Assessment Tools
For Excessive Sleepiness Evaluation
- Epworth Sleepiness Scale (ESS): Validated tool to assess subjective sleepiness 2
- Multiple Sleep Latency Test (MSLT): Objective measure of sleep propensity during waking hours 1, 2
- Maintenance of Wakefulness Test (MWT): Assesses ability to remain awake 3
For Sleep-Wake Pattern Documentation
- Sleep diaries: Minimum 7-day documentation showing relationship between work schedule and sleep disturbance 3, 1
- Actigraphy: Provides objective longitudinal data on sleep-wake patterns over the required documentation period 3
Associated Health Risks
SWD is associated with serious consequences that underscore the importance of accurate diagnosis:
- Increased accident risk: Higher risk of occupational and motor vehicle accidents 5, 6
- Cardiometabolic complications: Increased risk of obesity, insulin resistance, cardiovascular disease 3
- Cancer risk: Shift work has been associated with increased cancer risk 3
- Work-related injuries: Excessive daytime sleepiness increases injury risk 3