MSLT result must be positive, showing a mean sleep latency of less than or equal to 8 min-
utes and two or more sleep-onset REM periods in four to five naps.
Associated Features Supporting Diagnosis 
When sleepiness is severe, automatic behavior s may occur, with the individual continuing
his or her activities in a semi-automatic, ha zelike fashion without memory or conscious-
ness. Approximately 20%–60% of individuals experience vivid hypnagogic hallucinations