This disorder can have symptomatic periods, where "the time of high sleep propensity gradually shifts, such that patients experience daytime hypersomnolence and nighttime insomnia". In sighted people, the diagnosis is typically made based on a history of persistently delayed sleep onset that follows a<unk> -24-hour pattern. Hayakawa et al. (2005) reported on the basis of 57 cases of sighted patients that the average day length was<unk> .9 ± 0.4<unk> s (with the range of<unk> .4–26.5).
Non-24-hour sleep–wake disorder
Circadian rhythm sleep disorder
Delayed sleep phase disorder
Irregular sleep–wake rhythm
Advanced sleep phase disorder
Shift work sleep disorder
Excessive daytime sleepiness
Sleep state misperception