A Study to Investigate the Effect of XYWAV on Sleepiness, Polysomnography, and Functional Outcomes in Participants With Idiopathic Hypersomnia or Narcolepsy

Key Inclusion Criteria:

• Is 18 to 75 years of age (inclusive) at the time of signing the informed consentform (ICF)

• Has a primary diagnosis of IH meeting International Classification of SleepDisorders, Third Edition (ICSD-3) criteria or narcolepsy (Type 1 or Type 2) meetingICSD-3 or Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria.

• If not currently taking oxybate medication, has clinically significant symptoms ofExcessive daytime sleepiness (EDS) with an ESS score > 10 at Screening Visit 1. Ifcurrently taking oxybate medication, has an ESS score > 10 at the Baseline Visit 2polysomnography (after washout period). Note: Not applicable for participants who donot washout.

• If currently treated with anticataplectics and/or alerting agents, has been takingthe same dosage for at least 1 month prior to Screening Visit 1 and has no currentplans to adjust the dosage during the study period. Note: Alerting agents refer toeither traditional stimulants (eg, amphetamines, methylphenidates) or wake-promotingagents (eg, modafinils, pitolisant, solriamfetol).

Key Exclusion Criteria:

• Shows evidence of a previous untreated or inadequately treated sleep disorderconsidered by the investigator to negatively impact the conduct of the study,including sleep-disordered breathing, parasomnias, circadian rhythm sleep disorders,or restless legs syndrome determined by a previous sleep-laboratory diagnosis orinterview utilizing modules of the Diagnostic Interview for Sleep Patterns andDisorders.

• Shows evidence of untreated or inadequately treated sleep-disordered breathingduring Baseline Visit 2 polysomnography defined as an Apnea/Hypopnea Index (AHI) > 10, using the US Centers for Medicare and Medicaid Services rules (CMS.gov).

• Has a history or presence of any unstable or clinically significant medicalcondition (chronic pain condition that may impact sleep), behavioral or psychiatricdisorder (including active suicidal ideation or current or past [within 1 year]major depressive episode), or history or presence of another neurologic disorder orsurgical history that might affect the participant's safety and/or interfere withthe conduct of the study, in the opinion of the investigator.

• Has recently taken (ie, within 1 month prior to screening), is taking, or plans totake any of the following:

• A substance or medication contraindicated with XYWAV use, ie. specificallyalcohol and sedative hypnotics

• A medication with a known drug-drug interaction with XYWAV

• A medication that may have similar EEG effects to XYWAV

• Medications known to have clinically significant CNS sedative effects

• Other medications, natural health products, or substances from which theparticipant experiences clinically significant sedation