Shift Work Disorder
A circadian rhythm disorder occurring in people who work non-traditional hours, causing insomnia and excessive sleepiness that interfere with work and daily life.
What is Shift Work Disorder?
Shift Work Disorder (SWD) is a circadian rhythm sleep disorder affecting people who work during times that overlap with the body's natural sleep period, typically night shifts, early morning shifts, or rotating shifts. The disorder occurs because the internal circadian clock remains aligned with the day-night cycle even when work requires wakefulness at night. This leads to difficulty sleeping when time is available (during the day) and difficulty staying awake and alert during night work. Not everyone who works shifts develops SWD, but those who do experience significant impairment.
Prevalence
Approximately 20% of the workforce in developed countries performs shift work. Of these, an estimated 10-40% meet criteria for shift work disorder. The risk increases with rotating schedules, night shifts, and number of years of shift work. SWD is particularly common in healthcare workers, transportation workers, factory workers, and emergency responders.
Causes
SWD results from the conflict between work schedules and the circadian system. The internal clock is regulated by light exposure, and trying to sleep during daylight hours and work during the night runs counter to evolved biology. Factors increasing risk include: irregular or rotating schedules (worse than fixed night shifts), lack of control over schedule, long shifts, age (older workers adapt less well), individual circadian tendencies, family obligations limiting daytime sleep, and exposure to morning light after night shifts.
Symptoms
Insomnia during daytime sleep periods
Difficulty falling asleep, staying asleep, or sleeping long enough when trying to sleep during daylight hours. Daytime sleep is typically shorter and less restorative.
Excessive sleepiness during work
Difficulty staying awake and alert during night shifts, particularly during the circadian low point (2-6 AM).
Reduced total sleep time
Shift workers often get 1-4 hours less sleep than day workers, leading to chronic sleep debt.
Impaired concentration and performance
Difficulty focusing, slowed reaction times, increased errors, and reduced productivity, especially during night shifts.
Mood disturbances
Increased irritability, depression, and anxiety associated with chronic sleep deprivation and circadian disruption.
Physical health problems
Shift workers have increased rates of obesity, cardiovascular disease, gastrointestinal problems, and possibly cancer.
Social and family difficulties
Working while others are sleeping and sleeping while others are awake strains relationships and limits social participation.
Diagnosis
Self-Assessment Questions
If you answer yes to any of these questions, consider consulting a sleep specialist:
- 1Do you work night shifts, early morning shifts, or rotating shifts?
- 2Do you have difficulty sleeping during the day when you need to?
- 3Do you feel excessively sleepy or struggle to stay awake during your work shift?
- 4Is your total daily sleep less than when you worked a traditional schedule?
- 5Has shift work affected your mood, health, or relationships?
- 6Have these symptoms persisted for at least one month during shift work?
Diagnosis is based on the temporal relationship between shift work schedule and symptoms of insomnia and/or excessive sleepiness, with symptoms persisting for at least one month. Sleep logs and actigraphy help document the pattern.
Sleep Diary
A 2-week diary documenting sleep times, work schedule, and symptoms shows the relationship between work schedule and sleep problems.
Actigraphy
Objective measurement of sleep-wake patterns over 1-2 weeks, ideally including both work days and days off.
Polysomnography
Not routinely required but may be performed to rule out other sleep disorders like sleep apnea that can worsen shift work-related symptoms.
MSLT
The Multiple Sleep Latency Test may be used to document objective sleepiness in uncertain cases.
Epworth Sleepiness Scale
Questionnaire to quantify subjective sleepiness levels.
Treatment
Treatment focuses on maximizing sleep opportunity, optimizing the sleep environment for daytime sleep, using light strategically, and sometimes using medications to promote sleep or wakefulness at appropriate times.
Strategic Light Exposure
Bright light during the first half of the night shift helps promote alertness and adjust the circadian clock. Avoiding bright light (wearing dark glasses) on the commute home prevents morning light from counteracting adaptation.
Sleep Environment Optimization
Creating ideal conditions for daytime sleep: blackout curtains, white noise machine, cool temperature, phone silenced, and family members informed.
Planned Napping
A short nap (15-30 minutes) before the shift or during a break can reduce sleepiness. Longer naps may cause grogginess.
Sleep-Promoting Medications
Melatonin before daytime sleep may improve sleep. Prescription sleep aids (like zolpidem) may be used short-term for daytime sleep when other measures are insufficient.
Wake-Promoting Medications
Modafinil and armodafinil are FDA-approved for excessive sleepiness in shift work disorder. Caffeine can also help but should be avoided late in the shift.
Schedule Optimization
When possible, switching to a fixed schedule (rather than rotating), requesting forward-rotating shifts (day→evening→night), or limiting consecutive night shifts can help.
Lifestyle Adjustments
- •Create the darkest possible sleep environment for daytime sleep
- •Use earplugs and white noise to block daytime noise
- •Keep a consistent sleep schedule even on days off when possible
- •Wear dark glasses on the way home from night shifts to block morning light
- •Use caffeine strategically (early in shift only, avoid 4-6 hours before sleep)
- •Take a short nap before your shift when possible
- •Eat regular, healthy meals and avoid heavy meals during the shift
- •Exercise regularly but not too close to sleep time
- •Communicate with family about your sleep needs and create a quiet home environment
- •Consider the long-term health effects when making career decisions
Patient Support Resources
Find a Specialist
Search our directory for sleep clinics that specialize in treating shift work disorder.
Search Clinics