Irregular sleep-wake rhythm disorder

Introduction
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By Baruch El-Ad MD

Drs. Kataria and Vaughn explain the pathophysiology and treatment of this circadian rhythm sleep disorder. Irregular sleep-wake rhythm disorder (ISWRD) is characterized by the absence of circadian synchronization with an individual’s sleep-wake cycle. Irregular sleep-wake rhythm disorder is typically seen in patients with neurodegenerative disorders such as Alzheimer disease and dementia, and it is seen in institutionalized elderly patients; however, it has been also observed in patients with traumatic brain injury and neurodevelopmental disorders. Increased exposure to circadian zeitgebers, such as bright light and structured activities, may minimize the disturbance. Pharmacologic therapy with melatonin was generally ineffective in randomized control trials despite encouraging open studies in small series of pediatric patients thought to have irregular sleep-wake rhythm disorder. This review enables basic understanding of the circadian clock biology and its interactions with the sleep-wake cycle.

Key Points

  • Individuals with irregular sleep-wake rhythm disorder lack a clearly defined sleep period but demonstrate at least 3 irregular sleep bouts, which present as fragmented sleep at night and multiple naps during the day.
  • Irregular sleep-wake rhythm disorder is commonly seen in elderly institutionalized patients and in those with neurodegenerative disorders or neurodevelopmental disorders.
  • Loss of neurons in the suprachiasmatic nuclei (SCN), age-related changes in melatonin/pineal secretions, and decreased exposure to zeitgebers may contribute to the presence of irregular sleep-wake rhythm disorder.
  • Other medical, neurologic, or psychiatric disorders and medication side-effects may contribute to the sleep-wake cycle disruption.
  • Multimodal therapy that includes combination of timed light-melatonin treatment and nonpharmacological interventions like scheduled contacts, physical activity, and enriched environment may improve the sleep-wake pattern.H

In This Article

Introduction
Historical note and nomenclature
Clinical manifestations
Clinical vignette
Etiology
Pathogenesis and pathophysiology
Epidemiology
Differential diagnosis
Diagnostic workup
Prognosis and complications
Management
References cited
Contributors