Shift Work Sleep Disorder

Shift work sleep disorder (SWSD) is a sleep disorder that affects people who work irregular hours, typically between 10 P.M. and 6 A.M., or in shift rotations. The sleep schedules of these individuals are required to deviate from the natural circadian rhythm of the body, which normally regulates the sleep-wake cycle.

As a result, the sleeping patterns of people with SWSD are disrupted, which can cause them to have difficulty sleeping when they have time to sleep. Furthermore, SWSD can cause these individuals to become sleep-deprived and underperform at work due to excessive sleepiness.

Image Credit: Sushiman /

Circadian rhythm

SWSD occurs as a result of a misalignment between the actual and desired sleeping pattern of the individual. Generally, the sleeping patterns of these individuals differ as compared to what is considered as normal by society.

SWSD is classified as a circadian rhythm sleeping disorder, as it involves changes in sleep habits that differ from the normal sleep-wake cycle of the body. The circadian rhythm is the body's internal clock that responds to light cues in the surrounding environment to regulate the production and release of hormones that cause an individual to feel tired and alert at specific periods during the day.

Shift workers

Between 15-26% of the labor force in the United States and similarly developed nations work irregular hours, in the nighttime or in rotating shifts.

The vast majority of people who work in this manner can adjust and continue to perform well, despite changes in sleeping patterns. However, some individuals encounter significant difficulties when adjusting their internal body clock accordingly; therefore, for these individuals, SWSD is the presenting issue. SWSD occurs when there is a disparity between the sleep-wake cycles required by their work and circadian rhythm.

Despite the number of hours slept during the day, attempting to work when the circadian rhythm promotes sleep is extremely difficult if the internal clock does not change according to the needs of the individual.

Symptoms and complications

The symptoms of SWSD commonly include:

  • Difficulty sleeping at the desired bedtime
  • Excessive sleepiness during awake hours
  • Reduced concentration and performance at work
  • Headache
  • Fatigue

Additionally, as the performance of affected individuals during the day is limited, there is an increased risk of workplace accidents and errors, sick leave, and mood changes.

Sleep scientist Dr. Chris Harvey on the effects of night shift work


It is essential that people who work irregular hours or in shifts prioritize sleep and make arrangements to maximize sleep quantity and quality, even if it is at irregular hours.

Techniques to help aid in improving the quality of sleep include:

  • Minimize exposure to light shortly before planned bedtime
  • Follow a bedtime ritual to prepare the body and mind for sleep
  • Allow sufficient time to sleep (at least 7-8 hours a day)
  • Ensure that there is a positive sleep environment (e.g., low light and sound)
  • Reduce the intake of caffeine, alcohol, and nicotine before bedtime

It is also helpful for people who are having difficulties in maintaining a regular sleep schedule to keep a sleep diary to record their habits and identify any particular problems that could be addressed.

In some cases, changes to the work environment may be needed. This may include decreasing the number of consecutive night shifts or reducing the number of work hours. It is important that individuals affected by SWSD feel that they have enough time to sleep, in addition to spending time with family and participating in other activities.

Prescription medications are also sometimes indicated to help in the management of SWSD. This may include stimulant drugs, such as modafinil, to increase alertness at work or sleep aids to help with sleeping.


Further Reading

Last Updated: Dec 23, 2022

Yolanda Smith

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.


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