In the United States, 20% of employees work during shifts that are outside of the traditional 9:00 AM to 5:00 PM schedule, including many in the health care industry.1-3 Work schedules may include early morning, evening, night, or rotating shifts.4,5 Approximately 5% to 10% of shift workers have shift work disorder (SWD), a circadian sleep-wake cycle disorder defined by poor quality sleep that results in excessive sleepiness and insomnia.1-4 The lack of restful sleep increases the risk for drowsy driving, cardiovascular disease, metabolic disorders, cancer, and cognitive impairment.1-9 People working night shifts and rotating shifts are at higher risk for the disorder, with a prevalence of 14% and 8%, respectively.10

Primary care clinicians play an essential role in screening patients for SWD. A detailed clinical history, sleep log, and actigraphy help practitioners diagnose the condition.1-4 Patients with SWD often sleep less than the 7 hours recommended by the American Academy of Sleep Medicine (AASM) and the Sleep Research Society.6

Pathophysiology of Shift Work Disorder

The cause of SWD is the inability to sleep due to imbalance of the circadian rhythm and internal homeostatic sleep drives.2,4,5 The circadian rhythm is regulated by the suprachiasmatic nucleus (SCN), also known as the ‘master pacemaker,’ which is located in the hypothalamus.5,8 When light enters the eyes, photoreceptors send signals to the SCN to suppress the release of melatonin from the pineal gland, preventing the urge to sleep during the day.5,7 In shift workers who must sleep during the day, sleep eventually occurs due to the build-up of internal sleep pressure, but the circadian misalignment causes a decrease in sleep duration and inadequate sleep.4,5 In addition to light exposure, activity and meal timing signal the SCN to regulate the sleep/wake cycle.7 Shift work requires eating, socializing, and physical activity during hours that are at odds with the daily circadian rhythm, causing dysregulation of physiologic processes.5,7

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Adverse Health Outcomes of Shift Work Disorder

Shift work is a risk factor for hypertension, coronary heart disease, stroke, diabetes, obesity, and some types of cancers.1-8 The dysregulation of sleep affects the hormones leptin and ghrelin, which signal to the body to stop food intake and stimulate hunger, respectively.7 The altered eating patterns of shift workers — eating on an altered schedule, quickly devouring food, and skipping meals — dysregulates the hormonal balance and increases the risk for metabolic syndrome (abdominal obesity, hypertension, hyperlipidemia, and diabetes).7,11 Working nontraditional hours also can increase the risk of engaging in unhealthy behaviors such as smoking, excessive alcohol use, and decreased exercise, which also can lead to obesity.4,8

In 2007, the International Agency for Research on Cancer and the World Health Organization designated shift work as a possible carcinogen.12 A meta-analysis of 57 studies with more than 5.1 million participants noted that night shift workers have a 15% increased risk for cancer compared with those who work traditional hours, and the risk is cumulative over the years of shift work.13 Rotating shifts, which cause severe circadian disruption, pose the highest risk for cancer compared with fixed shifts (odds ratio [OR], 1.14; 95% CI,1.04-1.24).13 Shift workers are at particularly increased risk for breast (OR, 1.22; 95% CI, 1.08-1.32) and prostate cancers (OR, 1.26; 95% CI, 1.05-1.52).13 Carcinogenesis is attributed to decreased levels of nighttime melatonin, as well as decreased vitamin D level and circadian misalignment.13

Poor sleep causes fatigue and drowsiness, resulting in cognitive decline, which increases the incidence of work accidents and mistakes.3-5 Worker and public safety are at risk because shift workers include those in health care, protective services, and transportation roles.4 Shift work decreases overall mental performance; for example, 10 years of shift work equates to 6.5 years of age-related mental decline (2.5-point decrease on 0-100 scale).3,4 People with SWD often are tired while driving,5,9 and drowsy driving is reported to be the cause of 16.5% of fatal crashes.9 Those sleeping fewer than 6.75 hours had a 73% increased risk of falling asleep during the Multiple Sleep Latency Test.6

Recent research suggests that workers with a lower socioeconomic status (SES) have an even higher risk for health problems due to SWD.14 Workers with lower SES may have additional causes for insufficient sleep, such as increased exposure to environmental pollutants, psychosocial pressures, and neighborhood stressors.14

Evaluation and Diagnosis of Shift Work Disorder

Patient History

Patients with SWD often present with complaints of excessive fatigue, insomnia, poor sleep quality, and inability to stay asleep.1,2,4,5 It is imperative to distinguish SWD from other sleep disorders, such as obstructive sleep apnea, narcolepsy, restless legs syndrome, periodic limb movement disorder, and parasomnias.4,15 The assessment of excessive snoring and apneic breathing is more consistent with obstructive sleep apnea, whereas complaints of hallucinations or nightmares affecting sleep are more consistent with parasomnias.15 The inability to sleep because of a constant urge to move the legs is consistent with restless legs syndrome.15 Patients with SWD also may have comorbid sleep disorders, which are 18.8% more prevalent in those with SWD than those working traditional schedules.16

A complete clinical history, including medical, psychiatric, medication, sleep patterns, and work schedule histories, is essential.1,2,4.5 A comprehensive social history, including the use of tobacco, alcohol, and illicit drugs; physical exercise; and daily caffeine/energy drink consumption, also should be documented.8 There are 3 different, validated patient self-assessments for the evaluation of SWD (Table 1).1,4,5

Primary care providers receive little medical training about obtaining a sleep history from patients. One mnemonic device that can be helpful is BAMS-RN (Bedtime, Awakenings, Maladaptive sleep behaviors, Snoring, Rise time, and Naps).1 The patient completes a sleep log detailing sleep patterns for at least 7 days, describing bedtime, length of sleep, number of awakenings, caffeine or alcohol use at bedtime, snoring, and number of naps taken throughout the day.1,4

Diagnostic Tests for Shift Work Disorder

There are no laboratory or radiologic tests to confirm SWD. The AASM recommends actigraphy for at least 7 days in conjunction with a detailed history and sleep log (Table 2).1,4,15 An actigraphy monitor is a clinically validated device worn on the wrist to monitor sleep and wake cycles.1,4 It must be worn at all times — not just while working.2,4 Activity monitors are available on many smartwatches; however, the US Food and Drug Administration (FDA) has not approved these devices for clinical use. Nonetheless, if patients are unable to afford actigraphy, smartwatches are a viable substitution to facilitate monitoring. As patients with SWD are at higher risk for multiple medical conditions, clinicians should continue to recommend screening for diabetes, hypertension,
hyperlipidemia, and cancer.1-8 Psychological screenings assessing risk for depression, anxiety, and other psychological disorders also should be performed during each visit.8 Polysomnography is not recommended for diagnosis of SWD but may help rule out other sleep disorders.15

Clinical Management of Shift Work Disorder

Although the first recommendation for a patient diagnosed with SWD is to refrain from shift work, in most patients, quitting a job or changing the schedule is not an option.1,5 However, the following adjustments in shift work may be helpful5:

  • Maintaining a fixed shift schedule
  • Working <10 hours per shift
  • Working <4 shifts consecutively
  • Having at least 11 hours off between shifts
  • Scheduling shifts to follow a clockwise rotation

The clinical management of SWD is tailored to the patient based on symptoms. The AASM recommends both behavioral changes (Table 3) and medications (Table 4) for treatment of the disorder.6 Nonpharmacologic treatments entail lifestyle adjustments. The patient’s family and those living in the home must be aware of the adjustments and should offer support.17

There is no evidence indicating that any specific treatment has better efficacy. The goal of treatment is to realign the circadian rhythm, promote sleep, and reduce daytime sleepiness.17

Pharmacologic treatments are prescribed based on the patient’s complaints to treat insomnia and/or promote wakefulness.5 None of the treatments recommended for insomnia have been studied in SWD, but both treatments recommended to promote wakefulness are FDA-approved in patients with SWD.1,4,5 Pharmacological treatments offer immediate benefits, but all sleep-promoting agents may cause residual drowsiness affecting work performance.4,5 In addition, modafinil and armodafinil may exacerbate psychiatric conditions and must be prescribed carefully in those with a history of mania or psychosis.5

Patient Education

Shift work disorder puts patients at risk for drowsy driving. Patients must refrain from drowsy driving and arrange transportation when they experience excessive sleepiness. Assessment of the patient’s risk for a vehicular accident should include discussion of previous accidents or near misses.4 Educate family members about signs of comorbid disorders, such as apneic episodes, snoring, periodic limb movement, or restless legs syndrome.4,16 Encourage patients to seek support from family members for lifestyle adjustments.


After the initial diagnosis, patients should return for follow-up after a month to discuss the effectiveness of treatments and undergo screening tests.1,2,4,5 If Epworth Sleepiness Scale score remains high or is increasing, clinicians should refer patients to a sleep specialist for a Maintenance of Wakeful Test.1,4 If clinicians are concerned about narcolepsy, parasomnias, or obstructive sleep apnea, they should refer patients to a sleep specialist for polysomnography.2,4

Kimberly Sapre, DMSc, PA-C, CAQ-EM, practices emergency medicine in Falls Church, Virginia. She has 10 years of experience as a PA with previous experience in neurosurgery and interventional pain medicine.


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