In this study the investigators will evaluate chronotype, food intake pattern, and cardiovascular risk markers of elder individuals with OSA, in use of CPAP, when submitted to two weeks of CPAP withdrawal.

Obstructive sleep apnea (OSA) is a growing public health problem affecting up to 95% of older populations. This sleep disorder influences glucose metabolism, leptin and grelin levels, promotes sympathetic overactivity, and is associated to increased cardiovascular events. All awake-sleep processes are determined by clock-genes and by external factors such as sunlight, physical activity, feeding, sleep, and chronotype. Chronotype is the propensity for the individual to wake and sleep at a particular time during a 24-hour period, and is categorized as morning, intermediate or evening chronotype. Individuals with morning chronotype are more alert in the morning and choose an earlier bedtime. Individuals with evening chronotype have more inclination for evening activities and choose a later bedtime. And those classified as intermediate chronotype show low or no preference for either morning or evening hours for activities. Individuals with evening chronotype tend to have higher nocturnal food intake, body mass index (BMI), levels of stress hormones, and more sleep apnea episodes. In humans, changes in sleep pattern for a few days are sufficient to affect food intake pattern. Two days of partial sleep deprivation increases hunger and appetite for calorie-dense foods with high carbohydrate content. Food composition, quantity, timing, and rhythmicity of meals impact on microbiota and metabolism, increasing basal level of inflammation and age related diseases. The aging process comes with an increase in the molecules involved in hypercoagulable states, such as plasminogen activator inhibitor 1 (PAI-1), a protein induced by inflammatory mediators, which creates a prothrombotic state, resulting in a pathological deposit of fibrin followed by tissue damage. The increase in PAI-1 expression is related to the development of tissue pathologies such as thrombosis, fibrosis and cardiovascular disease. Adults with moderate-to-severe OSA have higher levels of PAI-1, and respond to two weeks of Continuous Positive Airway Pressure (CPAP) with a 50% reduction in this antifibrinolytic enzyme. The impact of CPAP use on chronotype, food intake pattern, and cardiovascular risk markers have never been studied in elder individuals with OSA.

Inclusion Criteria:

• Age 65 to 75 years
• Previous diagnosis of OSA with AHI> 30 events / hour
• Body mass index below 34,9 kg/m2
• Use of CPAP for more than one year, with an average duration of at least 6 hours per night, confirmed by the device's memory
• Evidence in the device that you have stopped using it previously, for at least two weeks, with no relevant symptoms
• Use of automatic CPAP device with full memory for at least one year, preferably using device model with internet data access
• Subjects physically active and willing to provide informed consent
• Subjects willing to attend visits and blood collections in series

Exclusion Criteria:

• History of myocardial infarction, stroke or transient ischemic attack (TIA) or peripheral vascular disease.
• History of chronic diseases such as diabetes mellitus ( A fasting plasma glucose (FPG) level of 152 mg/dL or A1C > 7,5 % ), uncontrolled severe hypertension (SBP >180 DBP > 110), renal failure on dialysis, cancer, autoimmune or liver disease
• A significant history of medical or psychiatric disease that may decompensate with altered sleep patterns or impair participation in the trial
• Severe or unstable clinical conditions that may be exacerbated by discontinuation of CPAP (cardiac, pulmonary, renal or other organ disorders not yet treated or worsening of symptoms in the last two months, eg cardiac arrhythmias, congestive heart failure and oxygen-dependent lung disease)
• Another primary sleep disorder that requires intervention with medications.
• Patients with unusual sleep or wake habits, including shift work.
• Professional driver or who crosses paths of more than one hour driving, in which the s sleepiness can be risk of accident.