This study is testing a medicine called clarithromycin to see if it helps people with excessive daytime sleepiness caused by conditions like narcolepsy (a disorder that makes people very sleepy during the day) and idiopathic hypersomnia (a condition where people feel overly sleepy without a known cause). Researchers want to find out how clarithromycin works to reduce sleepiness by looking at brain activity using special pictures called MRI (magnetic resonance imaging), inflammation, bacteria in the gut, and cerebrospinal fluid (the liquid around your brain and spine). The study will involve 92 people who will either take clarithromycin or a placebo (a fake pill) for 14 days.

• Participants must be between 18-60 years old and have narcolepsy or idiopathic hypersomnia.
• Participation requires stopping current wake-promoting medicines temporarily.
• People with certain other conditions may not be eligible.