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  • Updated 02.20.2021
  • Released 11.22.1993
  • Expires For CME 02.20.2024

Irregular sleep-wake rhythm disorder



Irregular sleep-wake rhythm disorder (ISWRD) is characterized by the absence of circadian synchronization with an individual’s sleep-wake cycle, which results in at least 3 major and several minor periods of sleep spread across the 24-hour period. Irregular sleep-wake rhythm disorder is typically seen in children with neurodevelopmental disorders and patients with neurodegenerative disorders, such as Alzheimer dementia, or institutionalized elderly patients, and has also been observed in patients with traumatic brain injury. Increased exposure to circadian zeitgebers, such as bright light and structured activities, may minimize the disturbance, but evidence is limited. Pharmacologic therapy with melatonin was generally ineffective in randomized control trials despite encouraging results in small open-label studies. 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 present as fragmented sleep at night and multiple naps during the day.

• Patients lack a clearly defined single major sleep period but demonstrate multiple irregular sleep bouts (at least 3).

• Irregular sleep-wake rhythm disorder is commonly seen in elderly institutionalized patients, adults with neurodegenerative disorders, or children or adults with 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 and melatonin treatment and nonpharmacological interventions like scheduled contacts, physical activity, and enriched environment may improve the sleep-wake pattern.

Historical note and terminology

The basis of biological rhythms and cycles in humans has long been a point of interest. Kleitman described a variety of changes across these approximately 24-hour cycles (13). The term “circadian” was introduced by Halberg in 1959 to account for both the day and nighttime phenomena of the rhythm (09; 16). Descriptions of aberrant rhythms followed, postulating that they may be an indication of health issues or have a direct impact on health (16). The current formal name established in the 3rd edition of the International Classification of Sleep Disorders is irregular sleep-wake rhythm disorder (01). However, irregular sleep-wake disorder was recognized as an issue involving the circadian pattern for decades prior to the classification (11).

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