delayed sleep phase syndrome
Definition A sleep disorder (OMIM:614163) characterised by an inability to fall asleep long after going to bed, due to delayed external day/night cues. Often linked to alcohol or sleeping pill abuse, DSPS may respond to bright light therapy given before bedtime.
Molecular pathology Individuals with aralkylamine N-acetyltransferase variant Thr-129–which is phosphorylated at residue 129 (of the 207 residue protein)–have an increased susceptibility to delayed sleep phase syndrome.
Synonym Night-owl insomnia