[Delayed sleep phase type sleep disorder and chronotherapy].

Delayed sleep phase type sleep disorder is a circadian rhythm disorder that results in symptoms of sleep-onset insomnia and difficulty awakening at a desired time. Patients with delayed sleep phase-type sleep disorder can be treated with chronotherapy, light therapy, vitamin B12, or melatonin. Chronotherapy is a behavioral technique in which sleep time is systematically delayed. Herein we report a 48-year-old woman that presented with delayed sleep onset and describe chronotherapy as a treatment approach.