1362 Behavioral Intervention for Non-24 Hour-Sleep-Wake Disorder in a Sighted Adolescent: A Case Report

Abstract Introduction Non-24-hour sleep–wake disorder (N24SWD) is characterized by a progressive daily drift of the circadian rhythm relative to the 24-hour light–dark cycle. While commonly associated with total blindness, N24SWD is rare among sighted individuals and even less frequently reported in adolescents, where it contributes to functional impairment, social withdrawal, and academic decline. We present a sighted 18-year-old with autism spectrum disorder (ASD) and severe sleep–wake drift who was successfully entrained using behavioral chronotherapy combined with light and melatonin interventions. Report of case(s) An 18-year-old male with ASD and social anxiety presented with progressively delayed sleep onset and offset, excessive daytime sleepiness, and significant school absenteeism. Baseline assessments showed ISI 17, PSAS-C 22, ESS 11, and MEQ 5. Sleep diaries demonstrated a ~2-hour daily phase delay, with sleep onset drifting from 22:00 to 16:00 over ten days, consistent with N24SWD in the absence of other sleep disorders. Treatment began with anchoring wake time at 12:00 for three days to relieve sleep debt, combined with evening light avoidance (00:00–04:00) and morning light exposure (12:00–13:00). The patient then undertook structured chronotherapy by delaying his sleep schedule by 120 minutes each day until achieving the target 23:00–07:00 sleep-wake schedule. Once stable, he introduced low-dose melatonin (1 mg) at 19:00, timed approximately two hours before estimated dim-light melatonin onset. Additional interventions included sleep restriction, stimulus control, blue-light blocking in the evening, and constructive worry techniques. At three weeks, his schedule stabilized between 23:00 and 07:30 with persistent increased sleep need. At six weeks, he maintained a consistent 23:00–08:00 schedule with sleep efficiency of 97.1%, ISI 4, PSAS-C 13, and ESS 7. Functionally, daytime alertness and work participation improved, with no adverse effects occurring throughout treatment. Conclusion N24SWD should be considered in sighted adolescents with continuous sleep–wake drift. In this case, circadian entrainment was successfully achieved using a structured behavioral and chronobiologic approach combining chronotherapy, timed light exposure, evening light restriction, and low-dose melatonin. Effective alignment of circadian phase resolved insomnia-like symptoms and improved daytime functioning. Support (if any) None