This study is testing a medicine called ALKS 2680 to see if it helps people with a condition called Narcolepsy Type 1 (NT1). NT1 makes you feel very sleepy during the day and can cause *cataplexy*, which is when your muscles suddenly get weak. The study will compare how people feel when taking ALKS 2680 tablets versus placebo tablets, which are look-alike tablets with no active medicine.

Key Points:

• The study will measure if symptoms like daytime sleepiness and cataplexy improve with ALKS 2680.
• Participants must not have other sleep disorders or be in another clinical trial.
• Women who are pregnant or breastfeeding cannot join the study.

The participants need to meet specific criteria, like being diagnosed with NT1 using special tests (such as PSG/MSLT* or checking CSF hypocretin-1 levels). They should not have other health issues that might affect the study. This research aims to find out if ALKS 2680 is a safe and effective treatment for NT1.