A Study of a Single Intravenous Infusion Dose of TAK-925 in Participants With Idiopathic Hypersomnia

The drug being tested in this study in participants with IH is called TAK-925. The study will have 2-treatment crossover groups. The study will evaluate the pharmacokinetics (PK), pharmacodynamics (PD), safety, and tolerability of a single intravenous (IV) dose of Dose A in participants with IH. The study will enroll 40 patients. Participants will be randomly assigned to one of the two treatment sequence groups as indicated below: * TAK-925 + Placebo * Placebo + TAK-925 On Day 1 of each treatment period, TAK-925 or placebo will be administered as a single 9-hour IV infusion. The multicenter study will be conducted in the United States and Japan. The overall duration of treatment in this study is approximately 41 days including screening up to 28 days, confinement for 6 days and end of study follow up telephone call on Study Day 11.