<unk>  is more common among middle and older adults. The estimated prevalence of<unk>  is about 1% in middle-age adults, and is believed to affect men and women equally. The disorder has a strong familial tendency, with 40-50% of affected individuals having relatives with<unk> . A genetic basis has been demonstrated in one form of<unk> , familial<unk>  (FASPS), which implicates missense mutations in genes hPER2 and CKIdelta in producing the<unk><unk>  phase phenotype. The identification of two different genetic mutations suggests that there is heterogeneity of this disorder.
Advanced sleep phase disorder
Delayed sleep phase disorder
Circadian rhythm sleep disorder
Non-24-hour sleep–wake disorder
Shift work sleep disorder
Nightmare disorder
Rapid eye movement sleep behavior disorder
Idiopathic hypersomnia