Narcolepsy (3.5e Flaw)
From D&D Wiki
You have difficulty staying awake.
Effect: You take a -6 modifier to any saves against sleeping effects; When you fail a save against a sleeping effect, the duration is increased by 1d3 rounds. You lose any immunity to sleeping effects, and cannot gain immunity to sleeping effects by any means.
Roleplaying Ideas: Sufferers of narcolepsy often have other sleep-related disorders such as insomnia, excessive daytime sleepiness and hypnagogic hallucinations.