Obstructive Sleep Apnea (OSA) is commonly associated with factors that increase cardiovascular risk, including Metabolic Syndrome (MS). There is a lack of well-controlled clinical studies investigating the independent effects of OSA in the development of cardiovascular disease, especially evaluating jointly mechanisms involved in these disorders such as inflammatory response, oxidative stress and vascular changes. The investigators hypothesized that in the absence of MetS, the mechanisms involved on cardiovascular consequences in OSA patients would be less important.

The purpose of this study is to analyze the effects of OSA in the absence of MS, on inflammatory, oxidative stress and vascular markers; to verify the influence of excessive daytime sleepiness (EDS) on the same parameters; and additionally verify the effects of nasal continuous positive airway pressure (nCPAP)in theses parameters.

Inclusion Criteria:

• male subjects
• apnea-hypopnea index > 15/h (OSA group)
• apnea-hypopnea index < 5/h (control group)

Exclusion Criteria:

• body mass index (BMI) > 30 kg/m2
• age > 60 years
• chronic obstructive pulmonary disease
• cardiac diseases
• diabetes mellitus
• metabolic syndrome according to modified National Cholesterol Education Program Adult Treatment Panel III criteria
• previous OSA treatment