What is the prevalence of Irregular Sleep Wake Type (IST)?
The prevalence of IST is unknown, but estimates suggest it is rare.41
IST is most frequently observed as a co-morbidity with neurological dysfunction, such as in patients with Alzheimer’s disease or other forms of dementia.42
41. Yamadera H, Takahashi K, Okawa M: A multicenter study of sleep-wake rhythm disorders: Clinical features of sleep-wake rhythm disorders. Psychiatry ClinNeurosci. 1996;50:195-201.
42. Reid KJ and Zee PC. “Circadian disorders of the sleep-wake cycle,” in Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, 2011, pages 470-482.