Inclusion criteria:  Individuals aged 65 to 80; both sexes; free and informed consent form previously signed for participation in the MEDIDAS cohort study; previous performance of outpatient polysomnography with adequate technical quality AHI ≤ 5 or ≥ 30 events/hour; previous blood collection between 7-9 am; questionnaires.  Exclusion criteria:  Have had treatment for sleep apnea; suffer from rheumatic or chronic diseases such as diabetes mellitus, heart failure, coronary artery disease, chronic renal failure or nephropathy (creatinine> 1.8 mg / dL), liver disease, history of stroke, aortic aneurysm, marked elevation in blood arterial pressure (> 180/110 mmHg), assessed by 24-hour ambulatory blood pressure monitoring (ABPM); cognitive deficit verified in the Mini Mental State Examination; diagnosis of Alzheimer's and Parkinson's.