A Switch Study From High-Sodium Oxybate to Xywav to Evaluate Changes in Blood Pressure in Participants With Narcolepsy

Key Inclusion Criteria: * Participants must be 18 to 70 years of age inclusive, at the time of signing the informed consent. * Participants have a documented diagnosis of Type 1 or Type 2 narcolepsy that meets International Classification of Sleep Disorders (ICSD)-3 or Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria. * Participants must have been receiving a total dose of high-sodium oxybate (eg, XYREM) of 6 to 9 g/night (inclusive) with twice-nightly dosing for a minimum of 6 consecutive weeks prior to screening. * If currently treated with stimulants and/or alerting agents or other medications known to affect BP, participant must have been taking the same dosing regimen for at least 2 months prior to screening and agree to take the same dose throughout the study. * If currently taking stable doses of antihypertensive therapies, participant must maintain these treatments at the same dose throughout the study unless otherwise advised by their medical care * Participant is male or female. A female participant is eligible to participate if she is not pregnant or breastfeeding, if she is a woman of nonchildbearing potential or is a woman of childbearing potential and using a contraceptive method that is highly effective. Key Exclusion Criteria: * History or presence of any acutely unstable medical condition, behavioral or psychiatric disorder (including active suicidal ideation), or surgical history that could affect the safety of the participant or interfere with study assessments or the ability of the participant to complete the study based on the judgment of the investigator. * Presence of significant cardiovascular disease or cardiovascular condition that in the investigator's opinion may jeopardize participant safety in the study, including screening ECG results. * Presence of atrial fibrillation detected on screening electrocardiogram (ECG). * Presence of resistant hypertension.