This study is for people with narcolepsy (a condition that makes you very sleepy) or idiopathic hypersomnia (a disorder causing excessive sleepiness without a known cause). It checks the safety and effectiveness of a medicine called ALKS 2680. To join, you must have already completed another related study. You also have to stop taking any current medicines for narcolepsy before joining. If you have a new health problem, are pregnant or breastfeeding, or are in another study, you cannot join. The study wants to see how well ALKS 2680 works over a long time.

• Participants will be monitored for safety while taking ALKS 2680.
• You must have finished a previous study with ALKS 2680 to join.
• You cannot join if you have health changes or are pregnant.