[Circadian rhythm sleep disorders].

BACKGROUND: Circadian rhythm sleep disorders often lead to sleepiness and insomnia. These disorders are characterized by a misalignment between the intrinsic circadian rhythm and the external social and physical environment. MATERIAL AND METHOD: This review is based on the authors' research and clinical experience and on articles identified by non-systematic searches in Pubmed and ISI Web of Knowledge. RESULTS: Circadian rhythm sleep disorders are categorized into six subtypes: Delayed sleep-phase disorder, advanced sleep-phase disorder, irregular sleep-wake rhythm, free-running disorder, jet-lag and shift work disorder. By administering light and/or melatonin at appropriate times in accordance with the phase response curves of light and melatonin, most of the circadian rhythm sleep disorders can be treated effectively. The documented effects of these interventions are good, but well-controlled studies with long-term follow-up are needed. INTERPRETATION: The best-documented approaches to treating circadian rhythm sleep disorders are light and melatonin; physicians can easily administer both treatments.