A Study of Danavorexton (TAK-925) in Adults With Obstructive Sleep Apnea

Inclusion Criteria: 1. Has OSA diagnosed according to the International Classification of Sleep Disorders-3 (ICSD-3) criteria and an AHI of 12-50 events/hour sleep (documented by an in-clinic PSG or at-home sleep test within the last 12 months). Participants who do not have PSG results from within 12 months available may be offered a screening home sleep test. 2. Those who use continuous positive airway pressure (CPAP), oral appliance, or hypoglossal nerve stimulator must be willing to forego this therapy during all in-clinic PSGs and during the home sleep test if one is required. 3. Has no known history of a sleep disorder other than OSA based on interviews at the screening visit, such as, for example, restless legs syndrome accompanied by periodic leg movements of sleep. 4. Has a regular bedtime (example, between 8 p.m. - 1 a.m.) and regular time in bed averaging between 6.0 and 10.0 hours/night, as verified by sleep tracking mat and sleep diary data. Sleep durations and bedtimes outside of this range can be discussed for inclusion on a case by case basis with the sponsor. 5. Has a body mass index (BMI) of 18 to 38.5 kilogram per square meter (kg/m\^2) inclusive. Exclusion Criteria: 1. Has an occupation requiring nighttime shift work or variable shift work within the past 2 months or has travelled with significant jet lag within 14 days before the study start or plans to travel with significant jet lag during the study. 2. Has nicotine dependence that is likely to have an effect on sleep (example, a participant who routinely awakens at night to smoke) or challenge the conduct of this study (smokes \>=10 cigarettes/day), or the participant is unwilling to discontinue all smoking and nicotine use during the confinement periods. 3. Has a caffeine consumption of more than 600 milligram (mg)/day for 7 days before Period 1 Day 1 (1 serving of coffee is approximately equivalent to 120 mg of caffeine; 16 ounces of cola or energy drink contain approximately 39 and 148 mg of caffeine, respectively).