Shift Work Disorder


Approximately one-fifth of workers work shifts that normally or occasionally fall during regular sleeping hours. A sleep disorder called shift work disorder (1) affects between 20% and 30% (2) of these shift workers, impacting their ability to sleep well and their daily performance. Learn about the causes of shift work disorder and how to improve your quality of life when working shifts.

What Is Shift Work Sleep Disorder?

Shift work disorder is a type of circadian rhythm sleep-wake disorder. The circadian rhythm (3) is a natural bodily rhythm responsible for regulating the sleep-wake schedule. For most people, this rhythm roughly follows a 24-hour pattern based on the sun: we sleep at night when it is dark, and we are awake during the daylight. Shift workers who work during nighttime hours may not be able to follow this sleeping pattern, leading some to develop ongoing sleep problems.

Causes of Shift Work Sleep Disorder

Shift work disorder is the result of needing to work at times when a person would usually be sleeping.

Individuals with shift work disorder may feel excessively sleepy at work and have trouble sleeping. When they do sleep, they may sleep up to four hours less than needed, and they may not wake up feeling well-rested. These problems are more common when working the night shift, early morning shift, rotating shifts, or extra-long shifts.

Shift work disorder differs from regular insomnia in that shift workers can usually sleep during times that feel more natural to them. In contrast, someone with insomnia may feel sleepy and have all the perfect conditions for sleep, but still be unable to sleep.

Risk Factors for Shift Work Sleep Disorder

Not all shift workers develop shift work disorder (4), but certain factors may raise the risk:

  • Being a morning person who works the night shift
  • Another sleep disorder
  • Stress and mental health issues
  • A lower tolerance for adapted sleep schedules
  • Older age
  • High caffeine intake
  • Nighttime worrying (5)
  • An irregular or unpredictable work schedule (6)
  • A long commute
  • Household responsibilities

Symptoms of Shift Work Sleep Disorder

To be diagnosed with shift work disorder, all four of these conditions must apply:

  • Difficulty falling or staying asleep or feeling excessively sleepy due to a shift work schedule that interferes with sleep
  • Symptoms lasting for three months or longer
  • Evidence of a disturbed sleep-wake schedule in a 14-day sleep diary and actigraphy test, which measures when someone moves and when they are at rest
  • Symptoms are primarily due to shift work and not another cause, such as medication or a mental health condition

People may experience shift work sleep disorder symptoms differently depending on the type of shifts they work. For example, those who work early morning shifts may have trouble waking up for work while it is still dark out and trouble sleeping after work while it is still daytime. Similarly, workers with night shifts may have trouble sleeping when they get off work as the sun rises. Individuals who work extra-long shifts and rotating schedules may feel additional fatigue beyond what is experienced due to the circadian rhythm no longer aligning with daylight hours.

One study found that shift workers with shift work disorder obtain less sleep (7), are less likely to catch up on missed sleep on days off, take longer to fall asleep, and obtain poorer-quality sleep than their non-shift-working colleagues. They also feel sleepier at work and make more mistakes at the beginning of a night shift.

How Does Shift Work Sleep Disorder Affect Day-to-Day Life?

Shift work sleep disorder can affect your work performance and increase your risk of being in a car accident. Additionally, the irregular sleep schedule can impact your social and family life. Ongoing sleep problems may also affect mood regulation and coping abilities.

Shift work disorder may cause sleep problems or excessive sleepiness even on days off. In the long term, shift work sleep disorder may worsen certain health conditions.

How Is Shift Work Sleep Disorder Diagnosed?

When you seek help for shift work disorder, your doctor will ask you to describe your sleep problems. They may also request that you keep a sleep diary and record your sleep time, work schedule, and any related notes over a span of two weeks. They may also conduct an actigraphy test, which involves asking you to wear a device that records your movements to see when you are awake and when you are asleep. During your awake hours, they might perform tests to check for excessive sleepiness.

If your doctor suspects a sleep disorder other than shift work sleep disorder, they may assess your sleep quality by ordering a sleep study that measures your brain waves while you sleep. Healthcare providers may also measure your levels of melatonin (8), the sleep hormone, to see if your circadian rhythm aligns with your work schedule.

Treatments for Shift Work Sleep Disorder

Treatments for shift work disorder focus on reducing excessive sleepiness and improving sleep quality through lifestyle changes and medication.

Lifestyle Changes

Before prescribing medication, most doctors recommend a series of lifestyle changes:

  • Be Consistent: If your work schedule permits it, try to wake up and go to sleep at approximately the same time every day, even on your days off.
  • Manage Light Exposure: Light promotes alertness. You may want to ask your workplace to install bright lights (9) if possible, and help your body wind down by avoiding light exposure (10) after your shift.
  • Schedule Shifts Strategically: Morning people tend to fare better on morning shifts, and night owls tend to fare better with night shifts, so try to schedule shifts that work best for your natural rhythm if you are able to. Also, try to avoid schedule changes that do not leave enough time for sleep between shifts (11).
  • Optimize Your Sleep Environment: Earplugs and an eye mask block noise and bright light, which could be helpful if you are sleeping during daytime hours.
  • Exercise: Regular exercise may protect against shift work sleep disorder.
  • Relax Before Bed: Going to sleep angry or worrying in bed can affect your sleep. It may help to create a relaxing bedtime routine.
  • Improve Sleep Hygiene: Healthy sleep hygiene habits include limiting caffeine and engaging in a consistent routine before sleeping each day.
  • Scheduled Naps: Planning a nap a few hours before your shift or partway through your shift may boost alertness.


If lifestyle changes do not help you get the sleep you need, your doctor may suggest sleep-promoting or wake-promoting substances (12). Your doctor might recommend taking melatonin supplements (13) before sleep, and having a cup of coffee before you need to work. It is important to address your concerns with your doctor in order to determine the best course of treatment.

When to Talk to Your Doctor

It is natural to have trouble sleeping when working shifts or adjusting to a new work schedule, but you should talk to your doctor if insomnia or excessive daytime sleepiness continue over time or interfere with your daily life. Seeking treatment is especially important for people who work in professions that require concentration or alertness (14), such as medical staff, firefighters, flight crew, and truck drivers, since shift work disorder can lead to increased mistakes and accidents.

Living With Shift Work Sleep Disorder

A strong social support system (15) may help you cope with stress, and has been linked to better sleep and less daytime sleepiness for some shift workers. You can also talk to your employer about following reasonable standards for shift scheduling (16), such as rotating shifts forward instead of backward, avoiding multiple consecutive shifts longer than 12 hours, and scheduling more important work duties for when workers are most alert.


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  3. 3. Accessed on August 23, 2021.
  4. 4. Accessed on August 23, 2021.
  5. 5. Accessed on August 23, 2021.
  6. 6. Accessed on August 23, 2021.
  7. 7. Accessed on August 23, 2021.
  8. 8. Accessed on August 23, 2021.
  9. 9. Accessed on August 23, 2021.
  10. 10. Accessed on August 23, 2021.
  11. 11. Accessed on August 23, 2021.
  12. 12. Accessed on August 23, 2021.
  13. 13. Accessed on August 23, 2021.
  14. 14. Accessed on August 23, 2021.
  15. 15. Accessed on August 23, 2021.
  16. 16. Accessed on August 23, 2021.

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