Obstructive Sleep Apnea (OSA) and Metabolic Syndrome: Role of Oxidative Stress

• Nonsmoker for at least 6 months
• No history of movement disorder during sleep, or circadian rhythm disorder
• No excessive daytime sleepiness
• No history of chronic insomnia, mood or affective disorders or other psychiatric disorders
• Participants maintain a regular sleep-wake pattern with an estimated sleep time between 6.5 and 10 hours per night
• Ability and willingness to avoid meat with its juice (gravy), cured or smoked foods and green leafy vegetables, fruit and fruit juices, food products or vitamin supplements containing vitamin C and E supplements for at least 1 day prior to and during the study periods
• Consumption of less than 1 alcoholic beverage per day
• Ability to understand the study and sign the informed consent
• Not currently pregnant
• Live within 45 miles of the study site
• No uncontrolled hypertension (blood pressure greater than 150/100)
• Willingness to avoid caffeinated beverages and food during the study protocol period

Participants With Sleep Apnea:

• Diagnosis of severe Obstructive Sleep Apnea and Hypopnea (OSAH) (RDI greater than 25) and initiation of positive airway pressure therapy more than 1 month before enrollment
• Must have had an adequate clinical titration of positive airway pressure therapy
• On positive airway pressure for at least 1 month with adherence of more than 5 hours of use per day with no history of snoring, no excessive daytime sleepiness and no reported observed apnea episodes on positive airway pressure
• Willing to sleep with and without positive airway pressure therapy as required by the study protocol

Exclusion Criteria:

• History or physical examination evidence of active coronary artery disease, heart failure, cardiomyopathy, syncope, potentially life-threatening arrhythmia, stroke, transient ischemic attack, neurologic impairment, renal, hepatic or thyroid disease (unless on stable thyroid replacement medication); history of diabetes mellitus; history of cancer within the past 10 years (other than basal cell carcinoma), venous thrombosis, or collagen-vascular disease or other condition that the investigators believe may be exacerbated by participation in the stud
• History of awakening with angina pectoris
• Currently taking medication for mood or affective disorders or that affect heme metabolism, autonomic nervous system or sleep architecture, or prescribed nitrates or corticosteroids
• Physician-diagnosed Alzheimer's or non-Alzheimer's dementia
• Previous surgery for sleep apnea
• Hematocrit less than 32
• Use of a hearing aid in one or both ears
• History of a bleeding disorder, abnormal bleeding, or known adverse reaction to heparin
• Inability to obtain venous blood or a low likelihood of obtaining venous access as required in this protocol
• History of migraine of a nature, frequency, and severity that, in the investigators' judgement, may be precipitated by participation in the protocol
• Presence of a potentially life-threatening dysrhythmia on the clinical diagnostic PSG
• History of motor vehicle accident due to falling asleep; not currently employed as a driver in the transportation industry or an airplane pilot
• Lipid-lowering agents for participants without a history of sleep apnea
• Individuals on positive airway pressure therapy for sleep apnea must not have lost more than 10 pounds of weight since starting this treatment