Non-24-hour sleep-wake syndrome in a sighted man: circadian rhythm studies and efficacy of melatonin treatment.
The case of a 41-year-old sighted man with non-24-hour sleep-wake syndrome is presented. A 7-week baseline assessment confirmed that the patient expressed endogenous melatonin and sleep-wake rhythms with a period of 25.1 hours. We sought to investigate the underlying pathology and to entrain the patient to a normal sleep-wake schedule. No deficiency in melatonin synthesis was found. Furthermore, normal coupling between the melatonin and sleep propensity rhythms was documented using an "ultrashort" sleep-wake protocol. Environmental light exposure was monitored for 41 days, and the circadian timing was calculated. Sensitivity to photic input was determined with light-induced melatonin-suppression tests. Three intensities (500, 1,000, and 2,500 lux) were examined during three separate trials. The 2,500-lux trial resulted in 78% suppression, but the lesser intensity exposures were without substantial effect. Thus, the patient appeared to be subsensitive to bright light. A 4-week trial of daily melatonin administration (0.5 mg at 2100 hours) stabilized the endogenous melatonin and sleep rhythms to a period of 24.1 hours, albeit at a somewhat delayed phase. A 14-month follow-up interview revealed that the patient continued to take melatonin daily, and his sleep-wake schedule was stable to a near 24-hour schedule.
McArthur
A J
AJ
Department of Psychiatry, School of Medicine, Oregon Health Sciences University, Portland 97201, USA.
Lewy
A J
AJ
Sack
R L
RL
D000328:Adult; D002940:Circadian Rhythm; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000097:blood / Q000627:therapeutic use*; D012893:Sleep Wake Disorders / Q000188:drug therapy*; D014851:Wakefulness
D008550:Melatonin