Advanced sleep phase syndrome is characterized by very early sleep onset and offset (summary by Jones et al., 1999).
Genetic Heterogeneity of Advanced Sleep Phase Syndrome
See also FASPS2 (615224), caused by mutation in the CSNK1D gene (600864) on chromosome 17q25, and FASPS3 (616882), caused by mutation in the PER3 gene (603427) on chromosome 1p36. [from
OMIM]