Understanding Narcolepsy: Types, Symptoms, Diagnosis, and Treatment
Sleep Medicine • Neurology • Psychiatry
Understanding Narcolepsy: Types, Symptoms, Diagnosis & Treatment
Narcolepsy is a chronic neurological disorder of excessive daytime sleepiness (EDS) with REM‑related phenomena (cataplexy, sleep paralysis, hypnagogic/hypnopompic hallucinations) and disrupted nocturnal sleep. Early recognition improves safety and quality of life.
Key clinical features
- Excessive daytime sleepiness (EDS): persistent, disabling sleepiness with irresistible sleep episodes.
- Cataplexy: brief, sudden loss of muscle tone triggered by strong emotions (pathognomonic for narcolepsy type 1).
- REM‑intrusion phenomena: sleep paralysis and hypnagogic/hypnopompic hallucinations.
- Nocturnal sleep disruption: fragmented sleep with frequent awakenings.
Types of narcolepsy
- Narcolepsy type 1 (NT1): EDS with cataplexy and/or low CSF hypocretin‑1 — often autoimmune loss of hypocretin neurons.
- Narcolepsy type 2 (NT2): EDS without cataplexy and normal or untested hypocretin; MSLT shows pathological sleep propensity but no cataplexy.
- Other/unspecified hypersomnia: where clinical features overlap or testing incomplete — consider specialist referral.
Assessment checklist
- Detailed sleep history: EDS onset, naps (frequency/duration/refreshing effect), cataplexy description, REM symptoms, nocturnal sleep quality, and impact on daily function.
- Medication/substance review: sedatives, stimulants, antidepressants (may affect MSLT), alcohol and illicit drugs.
- Screen for comorbid sleep disorders (OSA, RLS/PLMS) and psychiatric conditions (depression) that may mimic or worsen EDS.
- Use screening tools: Epworth Sleepiness Scale, sleep diaries and actigraphy to document sleep–wake patterns.
Investigations & diagnostic criteria
- Overnight polysomnography (PSG): performed to exclude sleep‑disordered breathing and ensure adequate sleep opportunity before MSLT.
- Multiple Sleep Latency Test (MSLT): objective daytime sleepiness measurement — mean sleep latency ≤8 minutes and ≥2 sleep‑onset REM periods (SOREMPs) supports narcolepsy diagnosis.
- CSF hypocretin‑1 assay: low levels (<110 pg/mL) confirm NT1 when available and appropriate.
- HLA DQB1*06:02: associated with NT1 but not diagnostic alone; helpful in ambiguous cases.
Management principles
- Safety & education: counsel on driving risks, workplace accommodations, scheduled naps, and symptom awareness for patients and family.
- Non‑pharmacologic strategies: planned short naps (10–20 min), structured sleep schedule, optimise nocturnal sleep, counselling and CBT for comorbid mood or coping difficulties.
- Pharmacologic therapy — EDS: first‑line wake‑promoting agents include modafinil/armodafinil, pitolisant, solriamfetol; traditional stimulants (methylphenidate, amphetamines) for refractory cases under specialist supervision.
- Pharmacologic therapy — cataplexy/REM symptoms: sodium oxybate is highly effective for cataplexy and disturbed nocturnal sleep; antidepressants (venlafaxine, SSRIs, tricyclics) can reduce cataplexy and REM intrusion symptoms.
- Multidisciplinary care: coordinate sleep medicine, neurology, psychiatry and occupational health for comprehensive management; review medications that affect sleep architecture or MSLT interpretation.
Medication highlights & cautions
| Medication | Indication | Notes/Cautions |
|---|---|---|
| Modafinil/Armodafinil | EDS | Often first‑line; monitor for headache, anxiety, rare severe skin reactions; potential for reduced efficacy over time. |
| Pitolisant | EDS, cataplexy (where licensed) | Histamine H3 antagonist/inverse agonist; may improve both sleepiness and cataplexy; monitor adverse effects. |
| Solriamfetol | EDS | Noradrenaline/dopamine reuptake inhibitor — effective for EDS; monitor BP and heart rate. |
| Sodium oxybate | Cataplexy and EDS | Highly effective for cataplexy and nocturnal consolidation; controlled substance with strict prescribing rules; sedating—nighttime dosing required. |
| Antidepressants (venlafaxine, SSRIs, clomipramine) | Cataplexy/REM symptoms | Useful for cataplexy but may affect sleep architecture and MSLT — coordinate timing of testing and treatment. |
Safety considerations
- Advise patients not to drive until EDS controlled; consider reporting requirements and occupational safety depending on jurisdiction and job risks.
- Monitor for psychiatric comorbidity (depression, anxiety) and suicidal ideation—treat concurrently.
- Be cautious using controlled substances (sodium oxybate, stimulants) in patients with substance use history—specialist oversight required.
Case vignette
Patient: S., 24, reports irresistible daytime sleep attacks, vivid hypnagogic hallucinations and episodes of sudden weakness with laughter (cataplexy). Overnight PSG normal; MSLT shows mean sleep latency 5 minutes with 3 SOREMPs — diagnosis: Narcolepsy Type 1. Management: safety counselling, scheduled naps, start modafinil for EDS and discuss sodium oxybate for cataplexy and nocturnal consolidation. Coordinate occupational advice regarding driving and university support.
தமிழில் — சுருக்கம்
நார்கோலப்சி என்பது நாளிலேயே தூக்கமடைந்து தூங்கு போகும் நோய்; கனவுகள், தூக்கத்தை தொடக்க/முடிக்கும் போது உடல் குறைதல் போன்ற அறிகுறிகள் இருக்கலாம். தீவிரமானவைகள் சிகிச்சைக்கிடைக்கும் — பாதுகாப்பு மற்றும் படிப்பு/வேலை ஆதரவு முக்கியம்.
When to refer
- Suspected narcolepsy or complex hypersomnolence—refer to sleep medicine for PSG/MSLT and specialist management.
- Recurrent injuries, uncontrolled cataplexy, failed first‑line therapy, or diagnostic uncertainty—specialist input and multidisciplinary care advised.
Key takeaways
- Suspect narcolepsy in young adults with disabling EDS, especially with cataplexy or REM‑intrusion symptoms.
- Diagnosis relies on PSG followed by MSLT, and CSF hypocretin where available; treatment combines behavioural strategies and pharmacotherapy tailored to EDS and cataplexy.
- Address safety (driving, occupational risk), coordinate multidisciplinary care and monitor for comorbid psychiatric conditions.