NARCOLEPSY TYPE 1 2 | SleepTech

Narcolepsy: Hypocretin Deficiency and REM Dysregulation

Narcolepsy is a central disorder of hypersomnolence. It is fundamentally a disease of state boundary instability, where features of REM sleep (atonia, dreaming) intrude into wakefulness, and wakefulness intrudes into sleep.

Narcolepsy Type 1 (NT1) vs Type 2 (NT2)

Feature	Type 1 (NT1)	Type 2 (NT2)
Cataplexy	Present	Absent
CSF Hypocretin-1	≤ 110 pg/mL (or < 1/3 of mean)	> 110 pg/mL
MSLT Criteria	MSL ≤ 8 min AND ≥ 2 SOREMPs*	MSL ≤ 8 min AND ≥ 2 SOREMPs
Pathophysiology	Autoimmune destruction of orexin neurons	Unknown (intact orexin signaling)

*A SOREMP (Sleep Onset REM Period) on the preceding nocturnal PSG can replace one of the required MSLT SOREMPs.

The Role of Cataplexy

Cataplexy is the sudden, transient loss of voluntary muscle tone triggered by strong, typically positive emotions (laughter, surprise). It represents the inappropriate activation of REM sleep atonia pathways during wakefulness. Patients remain fully conscious during a cataplectic attack.

Diagnostic Protocols: The MSLT

The Multiple Sleep Latency Test (MSLT) is required for diagnosing NT2 and is standard for NT1 (though CSF hypocretin can substitute). It involves 5 nap opportunities spaced 2 hours apart, following a standardized nocturnal PSG to ensure adequate prior sleep (usually ≥ 6 hours) and rule out other causes of sleepiness (e.g., severe OSA).

Detailed diagnostic criteria and physiological markers required to confirm this condition via polysomnography or clinical evaluation. Reliance on objective data is paramount.

Diagnostic Protocols

Refer to ICSD-3 classifications and ensure rule-out of confounding comorbidities prior to finalizing diagnosis.