Diagnostic criteria

There are two approaches to diagnosis:

• both of the following:
  
  
• almost daily daytime sleep episodes for 3 months
• cataplexy
  
  
• all four of the following:
  
  
• excessive daytime sleepiness or sudden muscle weakness
• any of:
  • sleep paralysis
  • hypnagogic hallucinations
  • automatic behaviour
  • disrupted nocturnal sleep episodes
• any of the following polysomnographic features:
• nocturnal sleep latency less than 10 min
  • nocturnal REM sleep latency less than 20 min
  • mean sleep latency less than 8 min on the multiple sleep latency test (MSLT)
  • two or more sleep onset REM periods during MSLT
• exclusion of medical or psychiatric causation