Apnea Positive Pressure Long-Term Efficacy Study

Inclusion Criteria:

   - Male or female adults age 18 years or older with a diagnosis of OSAS using clinical
   criteria defined by the study protocol

   - Study participation may require seven or more laboratory visits over six months

Exclusion Criteria:

   - Prior treatment for OSAS with continuous positive airway pressure or surgery

   - Potential sleep apnea complications that may affect the health or safety of the
   participant, including low blood oxygen, recent near-miss or prior automobile accident
   due to sleepiness, congestive heart failure, history of angina, coronary artery
   disease, myocardial infarction or stroke, cardiac rhythm disturbance, and chronic
   neurological disorders affecting neurocognitive abilities or daily function

   - The use of hypnotics, anxiolytics, sedating antidepressants, anticonvulsants, sedating
   antihistamines, stimulants or other medications likely to affect neurocognitive
   function and/or alertness

   - Respiratory disease requiring medications (unless on stable medications for 2 months)

   - Cancer, unless in remission for greater than one year and not taking exclusionary
   medications

   - Self-reported renal failure

   - Pregnancy anytime during a subject's participation

   - Psychiatric illness, as defined by a DSM-IV diagnosis, except for depression or mild
   anxiety

   - Narcolepsy, idiopathic hypersomnolence, DSM-IV chronic insomnia, restless legs
   syndrome, or rapid eye movement (REM) behavior disorder

   - Current use of diurnal or nocturnal supplemental oxygen

   - Significant vision, hearing, or coordination problems

   - Difficulty understanding or speaking English

   - Currently working night or rotating shifts

   - Consumption of more than 10 caffeinated beverages per day (approximately 1,000 mg per
   day)

   - Smokers whose habit interferes with the overnight polysomnogram or with the battery of
   testing during the day

   - Consumption of more than 2 alcoholic beverages per day

   - Any illicit drug usage or marijuana usage more than once a week

   - Any individual in the household currently on CPAP or on CPAP in the past

   - A score of 26 or less on the Mini Mental State Examination (MMSE)