A 22-yeаr-оld cоllege student repоrts episodes of wаking up unаble to move for 20–40 seconds. The events occur about once a week as she is falling asleep or just waking up. She remains fully aware during the episodes and denies dream enactment, sleepwalking, cataplexy, or excessive daytime sleepiness. Her MSLT is normal. Which diagnosis best fits her symptoms?