Editing Advanced sleep phase disorder (section)

== Epidemiology ==
ASPD is more common among middle and older adults. The estimated prevalence of ASPD is about 1% in middle-age adults, and is believed to affect men and women equally.  The disorder has a strong [[Familial sleep traits|familial tendency]], with 40-50% of affected individuals having relatives with ASPD.<ref name=":33"/> A genetic basis has been demonstrated in one form of ASPD, familial advanced sleep phase syndrome (FASPS), which implicates missense mutations in genes hPER2 and CKIdelta in producing the advanced sleep phase phenotype.<ref name=":33">{{Cite journal|last1=Zhu|first1=Lirong|last2=Zee|first2=Phyllis C.|date=2012|title=Circadian Rhythm Sleep Disorders|journal=Neurologic Clinics|volume=30|issue=4|pages=1167–1191|doi=10.1016/j.ncl.2012.08.011|issn=0733-8619|pmc=3523094|pmid=23099133}}</ref> The identification of two different genetic mutations suggests that there is heterogeneity of this disorder.<ref name=":25"/>