The POSAtive Study: Study for the Treatment of Positional Obstructive Sleep Apnea

Inclusion Criteria: 1. Subject is between the ages of 20 and 80. 2. Diagnosis of POSA meeting all the following criteria per in-lab control PSG (performed within 3 months of screening): * Total AHI \>15, or AHI \>10 and \<15 with ESS \>10 * Supine AHI at least twice the non-supine AHI * Non-supine AHI \<10 (\<5 in mild patients) * Supine time \>40% and \<60% 3. Subject understands the study protocol and is willing and able to comply with study requirements and sign informed consent. Exclusion Criteria: 1. Prior surgery to treat OSA (such as UPPP), or prior or current therapy or treatment for OSA, with the exception of PAP being used for split night PSG only. 2. A female of child-bearing potential that is pregnant or intends to become pregnant. 3. Any unstable or severe medical condition of any organ system including congestive heart failure, COPD, renal failure, neuromuscular disease, or at the discretion of the site Principal Investigator (PI). 4. Taking medication that may affect sleep, sleepiness, or alertness including hypnotics, sedatives, alerting agents, stimulants, opiates, sedating antidepressants, and anticonvulsants. 5. Oxygen use. 6. The presence of any other sleep disorder (central sleep apnea (CSA \>5), periodic limb movement disorder (PLMAI \>15), clinical diagnosis of insomnia or narcolepsy). 7. Excessive alcohol consumption (\>21 drinks/week). 8. The use of any illegal drug(s). 9. Night or rotating shift work. 10. Severe claustrophobia. 11. Shoulder, neck, or back complaints that restrict sleeping position. 12. Subject requires use of more than 2 pillows under the head while sleeping or sleeps in a bed/chair with raised upper body position.