Synopsis
Recognise narcolepsy and cataplexy, exclude common causes of excessive sleepiness, obtain valid overnight and daytime sleep testing, and plan safe behavioural, medicine and driving management.
- Narcolepsy causes persistent excessive daytime sleepiness with irresistible sleep episodes; brief naps are often refreshing but do not prevent recurrence later the same day.
- Type 1 narcolepsy is defined by cataplexy and/or documented hypocretin deficiency, whereas type 2 lacks cataplexy and requires objective sleep findings after competing causes are excluded.
- Cataplexy is sudden emotion-triggered loss of muscle tone with preserved awareness, ranging from jaw sag or slurred speech to knee buckling or collapse and usually lasting seconds to minutes.
- Sleep paralysis, vivid hypnagogic or hypnopompic hallucinations, fragmented nocturnal sleep and automatic behaviour support the diagnosis but occur outside narcolepsy and are not individually diagnostic.
- Exclude chronic sleep restriction, shift work, obstructive sleep apnoea, circadian disorder, sedating medicines, alcohol or drugs, depression and neurological disease before interpreting a multiple sleep latency test.
- A valid MSLT follows adequate documented sleep and attended overnight polysomnography, typically showing short mean sleep latency and at least two sleep-onset REM periods under accepted criteria.
- Management combines regular sleep scheduling, planned brief naps, education and specialist wake-promoting or anticataplectic medicines selected around occupation, cardiovascular, psychiatric and reproductive risks.
- Excessive sleepiness creates immediate driving and workplace hazards; apply current DVLA notification and licensing standards and advise the person not to drive while symptoms are uncontrolled.
Key red flags
Sleepiness while driving, operating machinery, working at height or caring alone for a child requires immediate activity restriction and occupational risk planning.
New hypersomnolence with focal neurology, headache, endocrine disturbance or rapid weight change requires assessment for secondary hypothalamic, inflammatory or structural disease.
Prolonged loss of consciousness, injury, exertional collapse, palpitations or post-event confusion is not typical cataplexy and needs cardiac or seizure assessment.
Pregnancy or pregnancy planning while taking modafinil requires urgent specialist and contraceptive review because of congenital malformation risk and reduced steroid contraceptive effectiveness.
Combining sodium oxybate with alcohol, opioids or other respiratory depressants can cause severe sedation and respiratory compromise.
Investigation priorities
Document sleep opportunity, timing, naps, shift work and symptom consistency before objective testing.
Management branches
Sleep attacks or unintended sleep occur repeatedly for at least several months.
- Distinguish sleepiness from fatigue and record night duration, shift work, snoring, apnoea, restless legs, medicines, alcohol, mood and medical illness.
- Ask specifically about emotion-triggered weakness, sleep paralysis, hallucinations, refreshing naps and safety-critical near misses.
- Correct inadequate sleep and obvious sedative contributors safely, screen for obstructive sleep apnoea and refer persisting unexplained sleepiness to a sleep service.
- Advise against driving or hazardous work while sleep attacks remain uncontrolled and apply current DVLA and occupational requirements.