“I fall asleep without warning in the day, even mid-conversation — and my knees buckle when I laugh”

NARCOLEPSY is chronic EXCESSIVE DAYTIME SLEEPINESS with irresistible SLEEP attacks (falling asleep mid-activity, unrefreshing despite adequate night sleep) plus REM-intrusion phenomena — SLEEP PARALYSIS, HYPNAGOGIC/hypnopompic HALLUCINATIONS and fragmented night sleep. The highly specific clue is CATAPLEXY — sudden, transient loss of muscle tone (knees buckling, head drooping, facial slackening) triggered by strong EMOTION, classically LAUGHTER, with PRESERVED consciousness (distinguishing it from syncope/seizure) — which characterises narcolepsy type 1 (orexin/hypocretin deficiency). Distinguish narcolepsy from other causes of excessive daytime sleepiness: insufficient/poor sleep, obstructive sleep apnoea (snoring/witnessed apnoeas/obesity), depression, drugs/alcohol, shift work and other hypersomnias, using the Epworth Sleepiness Scale (above 10 suggests excessive sleepiness) and a two-week sleep diary. Patients are frequently mislabelled as lazy or depressed and endure years of diagnostic delay, so take the symptoms seriously and validate the impact on studies, mood and relationships rather than dismissing them. Refer to a sleep/neurology service for diagnosis (polysomnography and Multiple Sleep Latency Test, ± CSF orexin) and treatment — sleep hygiene with scheduled naps, wake-promoting agents (e.g. modafinil, specialist-initiated; it can harm an unborn baby and reduces the effect of hormonal contraception, so effective contraception is needed, MHRA Drug Safety Update November 2020; solriamfetol per NICE TA758) for sleepiness, and specific agents for cataplexy — and address the DVLA/DRIVING implications (under current DVLA standards a Group 1 driver with narcolepsy must stop driving and notify the DVLA, with relicensing considered after satisfactory symptom control for at least 3 months confirmed by the specialist; Group 2 is much stricter) and the psychosocial/educational impact (Equality Act 2010 reasonable adjustments; mood). The skill is recognising the sleepiness + cataplexy + REM-phenomena pattern, not mislabelling it laziness/depression, and referring appropriately.