Inclusion criteria: We plan to include male or female subjects, age 18-80 with a diagnosis of medium-severe sleep apnea syndrome (defined by symptoms, a complaint of excessive daytime sleepiness, an Epworth sleepiness score >8, and an apnea / hypopnea index >15/h) and a resistant hypertension (systolic blood pressure >140 mmHg or >130 mmHg in patients with type II diabetes or chronic kidney disease, under treatment with three antihypertensive drugs including a diuretic).