During the night of each respective Polysomnography (PSG) assessments, subjects will be awoken at the approximate T-max of the active drug (2.5 hrs), with a matching placebo condition at the same time point using an identical responsivity protocol for each condition. The rationale for this is that t-max represents the time of greatest potential risk for a hypnotic in terms of balance, responsivity, and memory. Responsivity will be assessed using the Auditory Awakening Threshold test (AAT) and will be measured at 2.5 hours post dose for the Belsomra 10 and 20 mg (BEL), and placebo (PBO) conditions. Responsivity will be assessed at the approximate time above immediately after 5 minutes of consolidated (without arousals) NREM ( Non- rapid eye movement) stage 2 sleep has occurred.