Narcolepsy (3.5e Flaw)
From D&D Wiki
You have difficulty staying awake.
Effect: You suffer a -6 penalty to any saves against sleep effects; When you fail a save against a sleep effect, the duration is doubled. You lose any immunity to sleep 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.