Adolescent delayed sleep-wake phase with school failure (MEQ)

(i) Formulation. Delayed sleep-wake phase disorder (DSWPD): delayed sleep onset/offset, daytime impairment when forced to early schedule, and relatively restorative sleep on a free delayed schedule — the “holiday sleep test.” Contributing factors: developmental evening chronotype, evening phone light, possible ADHD traits, family conflict/stigma (“laziness”). Differentials: chronic insomnia disorder (less likely if free-day sleep is good), school refusal without circadian driver (can coexist), OSA (low pretest here), substance use, emerging mood disorder with reduced need (no elevated mood in stem), non-24 (no progressive free-running described).[1][5][6]

(ii) Assessment. Structured chronotype and schedule history (workday vs free-day mid-sleep); 1–2 week sleep diary; actigraphy if available; light/screen inventory; substances; mood/psychosis/suicide risk; ADHD screen after sleep opportunity considered; school attendance pattern and family dynamics; driving if relevant. PSG not first-line pure CRSWD. Consider DLMO if specialist pathway available for precision timing.[5][7]

(iii) Mechanisms. Two-process model: Process S (homeostatic) and Process C (SCN circadian). DSWPD is primarily Process C delay. PRC: morning light advances; evening light delays; melatonin roughly opposite light. Evening screens reinforce delay. Melatonin must be timed as a chronobiotic relative to desired bedtime/DLMO, not a random nightcap.[3][7]

(iv) Treatment plan. Psychoeducation to parents and young person — medical timing disorder, not moral failure. Fixed morning rise time with morning bright light; protect dark evenings (dim light, reduce phone in bed). Strategically timed melatonin: Sletten-order 0.5 mg orally about 1 hour before desired bedtime with behavioural scheduling (attempt sleep at desired bedtime most nights); Mundey-order teaching that advance magnitude depends on timing relative to DLMO; meta-analysis supports melatonin for DSWPD phase/latency outcomes.[2][3][4] Avoid long-term benzodiazepine/Z-drug as primary strategy.[6] Follow with diary/actigraphy; step to sleep medicine if refractory.

(v) System and pitfalls. School liaison: temporary adjusted start, graded return, medical letter explaining DSWPD. Reassess ADHD when sleep opportunity improves — do not attribute all inattention to character. Pitfalls: shaming, melatonin at wrong phase, escalating sedatives, missing mood disorder, chronotherapy without adherence support.[1][6]