The objective of the study is to define and compare clotting- fibrinolysis patterns, platelet function markers and endothelial dysfunction in patients with SAHS before and after treatment and normal controls age and weight matched.

The hypothesis of the study is the following: Patients with sleep apnea-hypopnea syndrome have higher risk of cardiovascular mortality during the night.

Respiratory alterations (hypoxia, hypoxia- reoxygenation) that these patients suffer during the sleep may induce modifications in platelet function, clotting-fibrinolysis factors and endothelial function, that may accelerate cardiovascular events during the night

DESIGN: Prospective and controlled study

METHODS: 20 SAHS patients and 20 controls will be studied. The study includes:

a) medical history; b) anthropometric variables (weight, height, body mass index, waist-hip ratio); c) sleepiness tested by Epworth scale; d) conventional polysomnography (PSG); e) testing every 4 hours for a 24 hours period: clotting-fibrinolysis factors (factor V, VII, VIII; C and S protein, plasminogen tissular activator (t-PA) and inhibitor of plasminogen activator (PAI-1); platelet activation markers (CD62, CD63 and GPIIb/IIIa) and endothelial dysfunction markers (endothelins, nitrites/nitrates and asymmetrical dimethyl-arginine); f) basic biochemical profile and hemogram. Patients will be revaluated after 6 months of CPAP treatment.

Inclusion Criteria:

• Apnea-Hypopnea Index > 15

Exclusion Criteria:

• Presence of any chronic disease
• Presence of cardiovascular disease
• Refusal to sign informed consent
• Drug addiction and/or alcoholism
• Any medication two weeks before