title: Larger phase angle between sleep propensity and melatonin rhythms in sighted humans with non-24-hour sleep-wake syndrome.
abstract: OBJECTIVE
  This study was aimed to clarify phase angle between sleep propensity and the circadian pacemaker in patients with non-24-hour sleep-wake syndrome (Non-24).
  
  
  METHODS
  A case-control study was underaken.
  
  
  METHODS
  Sighted patient with Non-24 (4 males and 1 female, aged 16 to 39 y), and sex- and age-matched healthy controls (12 males and 3 females, aged 19 to 35 y) participated the study. MEASUREMENT AND INTERVENTION: Following an actigraphic assessment of the sleep-wake cycle in their homes, the participants entered an ultra-short sleep-wake schedule together with simultaneous measurement of dim light melatonin rhythm after 24-hour sleep deprivation.
  
  
  RESULTS
  The period of the sleep-wake cycle observed at home was longer in the Non-24 patients (25.12 hours) than in the controls (24.02 hours, p<0.0001). The interval from sleep propensity (SP) onset to the melatonin midpoint (MLmid) was significantly shorter in the Non-24 patients than in the controls. The interval from the MLmid to the SP offset was significantly longer in the Non-24 patients than in the controls.
  
  
  CONCLUSIONS
  It was postulated that Non-24 sufferers' delayed SP onset relative to the circadian pacemaker may accelerate the light-induced phase-delay, leading to sleep-wake cycle that is longer than 24 hours.
authors.affiliation: Department of Psychophysiology, National Institute of Mental Health, National Center of Neurology and Psychiatry, Ichikawa, Japan. macoto@ncnp-k.go.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Kayo
authors.initials: K
authors.lastname: Shibui
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kamei
authors.forename: Takashi
authors.initials: T
authors.lastname: Ebisawa
authors.forename: Hirokuni
authors.initials: H
authors.lastname: Tagaya
authors.forename: Masako
authors.initials: M
authors.lastname: Okawa
authors.forename: Kiyohisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood / Q000378:metabolism*; D017286:Polysomnography; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism*
chemical_list: D008550:Melatonin