A Phase 3 Efficacy and Safety Study of HBS-301 in Participants With Idiopathic Hypersomnia (IH)

Inclusion Criteria: * Has a current documented diagnosis of IH per the International Classification of Sleep Disorders, Third Edition (ICSD-3) or Text Revision (ICSD-3-TR) criteria with confirmatory polysomnogram (PSG) with multiple sleep latency test (MSLT); and if applicable, an actigraphy report with sleep log on file that led to the diagnosis and was completed within the last 10 years. * Has moderate to very severe symptoms of IH. * If taking a permitted chronic concomitant medication or supplement, including nonprohibited antidepressants, must be on a stable dose for at least 3 months prior to Screening and agree to continue at that stable dose for the Double-blind Treatment Period of the study. Any treatment that could affect daytime sleepiness (including but not limited to stimulants, modafinil, and armodafinil) used on an as-needed basis is not permitted. * For participants being treated for obstructive sleep apnea (OSA) or other hypoventilatory conditions, must be compliant with their medical device or oral appliance as determined by the Investigator. Participants must maintain OSA treatment compliance throughout the study. Exclusion Criteria: * Has hypersomnia due to another medical disorder. * Has a history of pitolisant use within 5 half-lives prior to Screening. * Has a primary diagnosis of psychiatric illness that is not well controlled. * Has a history of moderate or severe hepatic impairment. * Has a body surface area (BSA)-corrected estimated glomerular fi…