A Study Evaluating the Efficacy and Safety of Xywav Expanded Dosing vs Placebo in Participants With Narcolepsy or IH

Inclusion Criteria: Has a primary diagnosis of IH or narcolepsy Type 1 or Type 2 (NT1 or NT2) Participants with a primary diagnosis of NT1 must have a history of at least 14 cataplexy attacks in a typical 2-week period, based on participant history at the time of diagnosis and prior to initiating treatment. Participants with a primary diagnosis of IH must have an average total nightly sleep [...] If not currently treated with oxybate, has clinically signif [...] th an Epworth Sleepiness Scale (ESS) score > 11 at screening and baseline. If currently treated with oxybate, must have documented im [...] lity, safety, [...]

Percentage of participants reporting minimally, much and very much worse in their CGIc questionnaire for IH or narcolepsy symptoms Percentage of participants reporting minimally, much and very much worse in their PGIc questionnaire for IH or narcolepsy symptoms Percentage of participants reporting m [...] Clinical Global Impression of Severity (CGIs) Scores for Narcolepsy/IH symptoms Change (CGIc)in scores Patient Global Impression of Severity (PGIs) Scores for Narcolepsy/IH symptoms Change in Patient Global Impression of Severity (PGIcPGIs) scoresScores for sleepiness Change in average total sleep t [...]

The trial has 23 treatment periods: open label titration and optimization period (OL-TOP), stable dose period (SDP) and the double-blind randomized withdrawal period (DBRWP). Participants will be evaluated by their disease cohort (Narcolepsy and IH). Once eligibility to participate in the trial is confirmed, eligible participants will begin theOL-TOP. Participants titrationwith narcolepsy and optimization treatment period where theyIH will be assigned to receive either cohort 1 or cohort 2. Participants assigned to Cohort 1 will receivea once-nightly expanded dosing of Xywav andor participants [...] [...]