This is a study to investigate the next-day residual effects of a single bedtime dosing of 5 mg and 10 mg of TS-142 in Japanese healthy elderly participants in double-blind manner.

Inclusion Criteria:

1. Subjects who are Japanese male or female aged 65 years or older at the time of obtaining informed consent
2. Subjects with a body Mass Index (BMI) from 18.5 to less than 25.0 and a body weight of 40.0 kg or over at the screening test
3. Subjects who are judged by the principal investigators or subinvestigators as an eligible for the clinical trial participation based on the results of tests conducted in the screening, VISIT 1 and prior to the administration of the investigational drug.

Other protocol defined inclusion criteria could apply.

Exclusion Criteria:

1. Subjects who are judged to have any disease by the principal investigator or sub-investigator and are not considered healthy
2. Subjects who have any unsuitable medical histories for participation in this clinical trial, including respiratory, cardiovascular, gastrointestinal, hepatic, renal, urological, endocrinological, metabolic, hematologic, immunologic, dermatological, neurological, or psychiatric diseases
3. Subjects who have any medical histories including sleep-associated symptoms, narcolepsy-like symptoms, suicidal ideation, or suicidal attempts.

Other protocol defined exclusion criteria could apply.