title: Association between delayed sleep phase and hypernyctohemeral syndromes: a case study.
abstract: OBJECTIVE
  We investigated whether the hypernyctohemeral syndrome (non-24-hour sleep-wake syndrome) may show a clinical association with the delayed sleep phase syndrome (DSPS) in a 39-year-old woman who developed sleep disturbances following a traumatic brain injury.
  
  
  RESULTS
  Sleep-wake log documentation and wrist-activity recordings for more than 6 consecutive months confirmed the patient's tendency to live on longer-than-24-hour "days." Episodes of relative coordination to the 24-hour day were also noted, suggesting that the patient was transiently in and out of phase with environmental synchronizers too weak to fully entrain her to the geophysical environment. Interestingly, we noted a tendency to initiate sleep between 3:00 am and 5:00 am and wake up from sleep between noon and 1:00 pm.
  
  
  CONCLUSIONS
  These results support an association between the hypernyctohemeral syndrome and the DSPS. This association may carry implications for the treatment of circadian rhythms disorders.
authors.affiliation: Center for Study and Treatment of Circadian Rhythms, Douglas Hospital Research Center, Montreal, Qc, Canada. boidia@douglas.mcgill.ca
authors.forename: Diane B
authors.initials: DB
authors.lastname: Boivin
authors.forename: Okan
authors.initials: O
authors.lastname: Caliyurt
authors.forename: Francine O
authors.initials: FO
authors.lastname: James
authors.forename: Colin
authors.initials: C
authors.lastname: Chalk
mesh_terms: D000328:Adult; D000647:Amnesia / Q000150:complications; D001930:Brain Injuries / Q000150:complications* / Q000175:diagnosis; D021081:Chronobiology Disorders / Q000150:complications; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D012720:Severity of Illness Index; D020178:Sleep Disorders, Circadian Rhythm / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D013577:Syndrome; D013997:Time Factors