What Is Shift Work Sleep Disorder?

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Shift work sleep disorder (SWSD) is a sleeping condition that is considered a circadian rhythm disorder. Basically, this means that people who are working during normal sleep hours can throw off their natural rhythm of sleepiness (circadian rhythm).

Learn how to tell the difference between SWSD and normal work fatigue. If you do have SWSD, learn how the diagnosis and treatment can be handled by your practitioner or healthcare professional.

What is shift work sleep disorder?
Verywell / Brianna Gilmartin 


SWSD occurs when a person has trouble adjusting to the work hours during the time period that most people sleep — such as working during a night shift. This results in a conflict in the normal waking/sleeping hours. For example, a person with SWSD may sleep for only a few hours, resulting in disruption of the quality as well as the length of sleep hours. 

The condition results in a feeling of fatigue, and eventually, exhaustion.

SWSD is known to interfere with a person’s normal level of work performance and put workers at risk of on the job injuries or mistakes. 

It’s important to note that not everyone who works a night shift has a shift work sleep disorder. Many people can adjust to the new sleep schedule within the first few weeks. Those who are "night owls," for example, may have an easier time adjusting to working a late evening shift. 

Early morning risers find it easier to adjust to shifts that begin before sunrise. But overnight or rotating shifts cause a problem for many people.


The symptoms of shift work sleep disorder are usually present as long as a person has a shift work schedule. “It can cause chronic sleep deprivation, in which a person never catches up on needed sleep and carries a significant 'sleep debt' with them. This kind of chronic loss of sleep has serious implications for health, productivity, and safety,” says the National Sleep Foundation.

Once the scheduled work hours no longer interfere with normal sleeping hours, the symptoms of SWSD may go away. However, some people continue experiencing sleeping problems even after changing their work hours. Symptoms of shift work disorder may include:

  • Excessive sleepiness during waking hours (and in general)
  • Inability to fall asleep or stay asleep
  • Sleep involving an insufficient number of hours
  • Sleep that doesn’t feel adequate and leaves a person feeling unrefreshed
  • Trouble concentrating
  • Irritability
  • Depression
  • Lack of energy
  • Headaches
  • Relationship problems

Most people experience some difficulty with these symptoms from time to time. For example, they may wake up after less than seven to nine hours of sleep or feel drowsy while on the job.

But, for those with shift work disorder, chronic drowsiness is an ongoing problem that causes adverse symptoms (such as irritability, lack of energy, or depression) and starts to interfere with work or family life.

Microsleeps and Excessive Sleepiness

According to the National Sleep Foundation, many shift workers experience something called microsleeps. This means that they simply fall asleep for very brief periods during work, family, or leisure activities as a result of excessive drowsiness. Microsleeps can result in dangerous accidents or mishaps if a person is driving or while on the job.

Problematic sleepiness differs from the normal decline in energy level that most people experience at certain times of the day. For example, problematic sleepiness occurs all day long — a person feels as though he or she is constantly fighting sleep. 

A key differentiating factor in excessive sleepiness due to shift work (compared to simply being tired) is that problematic chronic drowsiness interferes with a person’s ability to work, study, and socially interact.


The cause of shift work sleep disorder may include:

  • Working night shifts
  • Working overnight shifts
  • Working rotating shifts
  • Working very early morning shifts

What Are Circadian Rhythms?

The circadian rhythms are the body’s 24-hour internal clock, signaling the body of when to get sleepy and when to be alert by releasing certain hormones that change the body temperature and more.

One way the body regulates its waking/sleeping cycles is by producing a hormone called melatonin. The sun’s natural light is utilized to determine when and how much melatonin is produced. 

During SWSD, melatonin production oftentimes occurs when a person needs to be awake and alert on the job. When attempts are made to sleep during the day (when there is sunlight present) melatonin may not be produced. This may inhibit sleep. 


Sleep Education.org reports that the risks of sleeping disorders may include:

  • Mistakes at work
  • Frequent infections, flu, and colds
  • Increase in the time taken off work for illness
  • High cholesterol levels
  • Breast and prostate cancer
  • Heart disease
  • Obesity
  • Accidents when driving due to drowsiness or falling asleep at the wheel
  • Substance abuse (using drugs or alcohol to induce sleep)


When a shift worker has trouble falling or staying asleep or feels fatigued (even after a full night’s rest of seven to eight hours), this may indicate a diagnosis of SWSD.  

The diagnosis is usually made by a person’s self-report of sleep habits in addition to sleep study tests. The diagnosing healthcare provider may ask patients to record their sleep hours in a sleep diary. Questions about medical history and current medical problems may also be part of the diagnostic assessment. 

An in-lab sleep study or multiple sleep latency tests (MSLT) may also be done to rule out conditions, but usually only if narcolepsy or sleep apnea are suspected. The sleep study is conducted overnight in a clinic while the patient sleeps. The MSLT is a common test for narcolepsy, as it measures how fast a person falls asleep during the day.

SWSD can also be diagnosed with actigraphy (a movement sensor worn on the wrist that measures awake time and sleeps time), and melatonin sampling (hourly collections of saliva for melatonin analysis, to assess circadian patterns).


There are several approaches to the treatment of SWSD.

Lifestyle Changes

Treatment usually involves some lifestyle changes such as:

  • Keeping a regular sleep schedule each night (including nights that a person is not at work)
  • Minimizing exposure to sunlight after working a shift (to prevent the daytime biological clock from kicking in)
  • Taking naps when needed
  • Limiting caffeine intake at least four hours before going to bed.
  • Eating a healthy diet with foods high in antioxidants (to help boost the immune system)
  • Creating a dark environment for sleeping (using room darkening shades)
  • Asking roommates or family members to keep the noise level down when possible during the daytime sleep hours
  • Avoiding exposure to sunlight when planning to sleep during the day (wearing sunglasses if going outside is necessary)
  • Using white noise to cover up any loud sounds while sleeping (such as neighbors cutting grass)
  • Taking a melatonin supplement; it is best to consult with your healthcare provider prior to adding any supplement to your diet, including melatonin

Medical Procedures

There are also a variety of medical procedures that may be viable options. Be sure to discuss what is best for your individual case with your practitioner or healthcare professional.

Bright Light Therapy: This is an artificial type of light used during the day that can help the body’s circadian rhythms adjust to transition in sleeping and waking hours.

Sleep Medication: A person's healthcare provider may prescribe some type of sleep-inducing medication to help a person with SWSD sleep better. Sleep medications can also cause serious side effects (such as parasomnias). 

Parasomnias involve actions during sleep in which a person has no control, such as sleepwalking. 

Most prescription sleeping medications are addictive, requiring more and more pills to get the same effect as the body grows a tolerance.  Therefore, this type of medication is best if used during a short time span.

Supplements: Natural supplements such as melatonin may be a better choice for those needing to take some type of sleep-inducing agent. 

Melatonin is all-natural, it is not addictive, and it can be taken long-term without the well-known side effects of prescription medications (though you should still consult with your healthcare provider prior to taking any supplements regularly). Melatonin should be taken a few hours before a person plans to sleep.

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By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.