The reasoning
Narcolepsy = failure to maintain stable wake–sleep boundaries, with REM intruding into wakefulness. Type 1 involves loss of hypocretin/orexin neurons. Tetrad: excessive daytime sleepiness + cataplexy (sudden emotion‑triggered loss of muscle tone, consciousness preserved — pathognomonic when present) + sleep paralysis + hypnagogic/hypnopompic hallucinations. Diagnosis: PSG + MSLT (short sleep latency, ≥2 sleep‑onset REM periods), after excluding insufficient sleep/shift work/OSA.
The two discriminators that matter
- Narcolepsy vs ordinary sleepiness: ordinary sleepiness is explained by insufficient/poor‑quality sleep; narcolepsy is pathological ± cataplexy/REM intrusion.
- Sleep‑transition hallucinations vs psychosis: hypnagogic/hypnopompic phenomena and sleep paralysis are state‑boundary events, not psychosis. This is the phenomenology principle (Concept 5) in action — when it occurs reclassifies the symptom.
Management (orientation)
Sleep hygiene + scheduled naps; wake‑promoting agents (modafinil), and for cataplexy agents such as SNRIs or sodium oxybate — specialist‑led.
Pitfalls
- Misreading hypnagogic hallucinations/sleep paralysis as a psychotic disorder.
- Diagnosing narcolepsy without excluding chronic sleep deprivation/OSA.
Pearls
- 🎯 EDS + cataplexy = narcolepsy until a sleep study says otherwise.
- 🩺 Sleep‑transition hallucinations are near‑normal — timing reclassifies them.
Next → The sensorimotor sleep disorder easily confused with a drug side‑effect (Concept 39).