Sleep, fatigue and circadian disorders in adolescents — formative SAQs

SAQ 1 — The tired, late-rising teenager (10 marks)

A 15-year-old girl is referred because she "can't get up" and falls asleep in morning classes. On weeknights she is in bed by 23:00 but does not fall asleep until about 01:30 and rises at 06:45, sleeping roughly five hours. On weekends she sleeps from 02:00 to 11:00 and feels well. Her mood and examination are normal. ^{[9] [10]}

Questions

1. What is the most likely mechanism of her sleep problem, and which three features of the history support it? (4 marks) ^[9]
2. Outline the stepped-care management you would offer, naming the specific components. (6 marks) ^{[7] [15]}

Model answer

Diagnosis and pattern (4). The likely mechanism is delayed sleep-wake phase disorder (DSWPD) — sleep of normal length and quality occurring at a delayed clock time. The three supporting features are: (1) a very late sleep onset that is involuntary, not a choice; (2) normal, refreshing sleep of about nine hours when allowed a free schedule at the weekend; and (3) a marked weekend–weekday rebound (02:00 to 11:00 versus 01:30 to 06:45), reflecting a delayed biological clock colliding with a socially fixed wake-time. This is not insomnia (she sleeps well once asleep) and not simple insufficient sleep (the opportunity is there, but the clock will not allow it). ^{[9] [10]}

Stepped-care management (6). Begin with the universal measures: a consistent rise time held seven days a week (the anchor for the clock), an adequate eight to ten hour sleep opportunity, and protection from evening light and screens for an hour before bed. For the phase advance specifically, combine three components: (1) bright light for 30 to 60 minutes on waking, to advance the circadian signal; (2) low-dose melatonin in the range of roughly 0.3 to 5 mg taken about three to five hours before the current habitual sleep onset, gradually moved earlier with the schedule (off-label in paediatrics in many regions, with specialist input); and (3) a gradual earlier rise time, shifted 15 to 30 minutes every few days and held at weekends. Add a two-week sleep diary to monitor progress, review at four to eight weeks, and safety-net for cataplexy, snoring with apnoea, or mood decline. ^{[7] [15]}