Key Inclusion Criteria:  Males and females between 18 and 65 years of age, inclusive Diagnosis of narcolepsy according to ICSD-3 (International Classification of Sleep Disorders, 3rd Edition) or Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) criteria Body mass index from 18 to 40 kg/m2, inclusive Consent to use a medically acceptable method of contraception Willing and able to provide written informed consent  Key Exclusion Criteria:  Female subjects who are pregnant, nursing, or lactating Any other clinically relevant medical, behavioral, or psychiatric disorder other than narcolepsy that is associated with excessive sleepiness History or presence of bipolar disorder, bipolar related disorders, schizophrenia, schizophrenia spectrum disorders, or other psychotic disorders according to DSM-5 criteria Use of any over-the-counter (OTC) or prescription medications that could affect the evaluation of excessive sleepiness Use of any medications that could affect the evaluation of cataplexy Received an investigational drug in the past 30 days or five half-lives (whichever is longer)