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Irregular sleep-wake rhythm disorder is a circadian rhythm sleep-wake disorder involving disrupted sleep patterns that don’t fit a normal circadian cycle. Typically, the circadian rhythm governs sleep-wake cycles and regulates a predictable pattern of sleep and wakefulness over the course of 24 hours. People with this rare neurological condition lack a defined circadian rhythm or normal sleep schedule. They may get enough sleep overall with 8-9 hours of total sleep in a 24-hour period, but don’t have a predictable sleep pattern.
People with irregular sleep-wake rhythm disorder take multiple daytime naps, with fragmented, shortened nighttime sleep. The naps vary in length, but often fall into several 1-4 hour sleep periods throughout the day or night. The longest sleep period usually occurs between 2 a.m. and 6 a.m. Over time, these poor sleep patterns lead to fatigue and difficulty with daily tasks.
People with this sleep disorder generally experience:
This condition is rare, and the prevalence is not known. However, the disorder most commonly affects older adults in nursing homes, hospitals or other institutions, and those with neurodegenerative disorders like Alzheimer’s disease and dementia.
The absence of regular exposure to light and mealtimes is thought to contribute to irregular sleep-wake rhythm disorder. These “zeitgebers” act as cues that regulate biological rhythms, including sleep. When older people living in nursing homes, hospitals, or group homes aren’t exposed to these social cues, their sleep patterns may fall out of alignment.
Age-related changes to hormone levels are known to affect the body’s circadian rhythms, and may play a role in irregular sleep-wake rhythm disorder. Changes to the part of the brain involved in regulating biorhythms may play a role in this condition. Researchers haven’t uncovered a specific genetic link for irregular sleep-wake rhythm disorder, but some research suggests a genetic component to the disrupted sleep patterns seen in irregular sleep-wake rhythm disorder.
Doctors examine a patient’s self-reported symptoms and review sleep patterns to diagnose irregular sleep-wake rhythm disorder. A sleep specialist might use actigraphy or a patient’s sleep diary to determine whether the disrupted sleep patterns fit the characteristics of irregular sleep-wake rhythm disorder: at least three naps or sleep periods within 24 hours.
As with other circadian rhythm sleep-wake disorders, treatment for irregular sleep-wake rhythm disorder usually involves a combination of behavioral changes, light therapy, and melatonin to regulate circadian patterns.