Narcolepsy is a condition that makes people very sleepy during the day. This study looks at a new treatment called JZP441 for narcolepsy type 1 (NT1). The study checks how safe and effective JZP441 is for adults with NT1. It is a Phase 1b study, meaning it's an early stage of testing. The study uses a placebo (a fake treatment) to compare with JZP441. Participants won't know if they're getting JZP441 or placebo, but the sponsor will know. The study checks how the body processes JZP441, which is called pharmacokinetics (PK).

• The study needs multiple visits and tests over time.
• Only adults aged 18 to 64 who meet specific health criteria can participate.
• Participants should not have certain health problems or be on other medications that may interfere with the study.