A Study to Assess the Effect of Seltorexant Compared to Placebo on Respiration During Sleep in Adult Participants With Obstructive Sleep Apnea

Inclusion Criteria:

- Participant must be a women of non-childbearing potential (WONCBP) or man. A WONCBP is
defined as: a) Postmenopausal (postmenopausal state is defined as no menses for 12
months without an alternative medical cause. A high follicle stimulating hormone (FSH)
level in the postmenopausal range may be used to confirm a postmenopausal state in
women not using hormonal contraception or hormonal replacement therapy; b) Permanently
sterile (permanent sterilization methods include hysterectomy, bilateral
salpingectomy, bilateral tubal occlusion/ligation procedures, and bilateral
oophorectomy

- Meet the International Classification of Sleep Disorder diagnostic criteria for
obstructive sleep apnea (OSA) based on the investigator's assessment with or without
sleep study. The OSA diagnosis can be confirmed by previous sleep studies, appropriate
documentations (for example, medical records or letters from treating physicians) or
documented conversation with the treating physician

- Mild to moderate OSA, defined as AHI greater than or equal to (>=)5 to less than
(<)30, based on screening polysomnography (PSG)

- Body mass index (BMI) between 18 and 40 kilogram per meter square (kg/m^2) (inclusive)
(BMI = weight/height^2)

- Must be otherwise healthy based on physical examination, medical history, vital signs,
12-lead electrocardiogram (ECG), and clinical laboratory tests performed at screening.
If there are abnormalities, they must be consistent with the underlying illness in the
study population. If the results of the clinical laboratory tests are outside the
normal reference ranges, the participant may be included only if the investigator
judges the abnormalities from normal to be not clinically significant or to be
appropriate and reasonable for the population under study

Exclusion Criteria:

- Has a history of, or current signs and symptoms of, severe renal insufficiency
(creatinine clearance <30 milliliter per minute [mL/min]); moderate to severe hepatic
insufficiency (Child-Pugh Score >=7), significant or unstable cardiovascular,
respiratory, gastrointestinal, neurologic, hematologic, rheumatologic, immunologic, or
endocrine disorders (including uncontrolled hypo- or hyperthyroidism or diabetes
mellitus). Participants with diabetes mellitus who are under good control (hemoglobin
A1c [HbA1c] <= 8.5 percent [%] and fasting glucose <=140 milligram per deciliter
[mg/dL] at screening) may be eligible to participate if otherwise medically healthy,
and if on a stable regimen of glucose-lowering medications for at least 2 months prior
to screening

- Screening PSG with oxygen (O2) saturation <=80% for >=5% of total sleep time (TST)

- Screening PSG with >=10 periodic limb movements per hour associated with an arousal

- Currently using or used within 7 days of screening a continuous positive airway
pressure (CPAP), a dental appliance, or home oxygen use for OSA, or required to use
any of them for the duration of the study

- Has other respiratory disorders such as chronic obstructive pulmonary disease (COPD)
or asthma that need systemic and/or inhaled steroids, bronchiectasis, or emphysema,
documented by history or physical examination