Non 24 hour sleep wake disorder
Other Names for this Disease
- Circadian rhythm sleep disorder, free-running type
- Hypernychthemeral syndrome
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 Non 24 hour sleep wake disorder can also affect sighted people. The cause of the disorder in these cases is incompletely understood, but studies suggest melatonin levels play a role.Non 24 hour sleep wake disorder refers to a steady pattern of one- to two-hour delays in sleep onset and wake times in people with normal living conditions. This occurs because the period of the person's sleep-wake cycle is longer than 24 hours. The condition most commonly affects people who are blind, due to an impaired sense of light-dark cycles.
Last updated: 6/3/2014
- Judd BG, Sateia MJ. Classification of sleep disorders. In: Basow M. UpToDate. Waltham, MA: UpToDate; 2014; Accessed 6/2/2014.
- Hayakawa T, Uchiyama M, Kamei Y, Shibui K, Tagaya H, Asada T, Okawa M, Urata J, Takahashi K. Clinical analyses of sighted patients with non-24-hour sleep-wake syndrome: a study of 57 consecutively diagnosed cases. Sleep. August 1, 2005; 28(8):945-52. http://www.ncbi.nlm.nih.gov/pubmed/16218077. Accessed 6/2/2014.
- Uchiyama M et al. Larger phase angle between sleep propensity and melatonin rhythms in sighted humans with non-24-hour sleep-wake syndrome. Sleep. 2002 Feb 1; 25(1):83-8. http://www.ncbi.nlm.nih.gov/pubmed/11833864. Accessed 6/3/2014.
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