A Study of ACT-541468 in Healthy Japanese and Caucasian Subjects

Key Inclusion Criteria: * Signed informed consent form; * Healthy male and female subjects aged between 20 and 50 years (inclusive) at screening; * Negative serum pregnancy tests at screening and negative urine pregnancy test at Day 1 for women of childbearing potential and agreement to use a reliable method of contraception for at least 90 days after last study drug intake; * Body mass index (BMI) of 18.0 to 26.0 kg/m2 (inclusive) at screening; * Healthy on the basis of physical examination, cardiovascular assessments and laboratory tests; * Caucasian or Japanese ethnicity. Japanese subjects only: * must be of native Japanese descent (all parents/grandparents of Japanese descent); * must not have been away from Japan for more than 10 years (at screening visit); * lifestyle should not have changed significantly since relocation from Japan. Key Exclusion Criteria: * Any contraindication to the study treatments; * History or clinical evidence of any disease or medical / surgical condition or treatment, which may put the subject at risk of participation in the study or may interfere with the absorption, distribution, metabolism or excretion of the study treatments; * History of narcolepsy or cataplexy or modified Swiss narcolepsy scale total score \< 0; * Any circumstances or conditions, which, in the opinion of the investigator, may affect full participation in the study or compliance with the protocol.