Normotensive OSA Patients With Dipper Circadian Blood Pressure Pattern

1. Recruitment: Normotensive subjects referred to the sleep unit of the Hospital Santa Maria (Spain) who are diagnosed of severe OSA (AHI≥30) by a sleep study and dipper circadian blood pattern confirmed by ABPM and who do not present significant somnolence (Epworth≤18) will be included in the study. 2. Definition of the groups: Patients will be randomized to receive one of the following treatments: 1. CPAP: Patients who will receive CPAP treatment. The CPAP titration will be carried out with an automatic or manual CPAP according to usual clinical practice. 2. Conservative treatment: Patients who will receive conservative treatment based on hygienic-dietetic measures. 3. Randomization: It will be carried out with an automated platform 4. Duration of the treatment: All patients randomized to CPAP will begin treatment as soon as possible after randomization, and will continue treatment until the study ends (3 months). Patients who interrupt treatment will be excluded from the study. ABPM and blood sample collection will be performed on all included patients at the beginning of the study and at 3 months under treatment (CPAP or conservative care). 5. Follow-up: All patients will be evaluated at the beginning of the study (T0), at first month (T1) and at three months (T2), during the follow-up period.