 The main purpose of this study is to investigate if treatment of obstructive sleep apnea syndrome OSAS by continuous positive airway pressure CPAP given by a traditional CPAP device administering a fixed air pressure, or by one automatic CPAP device Somnosmart2, Weinmann, Hamburg administering variable pressures, have different effects on sympathetic nervous system tone as reflected by urinary excretion of norepinephrine and its catabolite normetanephrine and on blood pressure. 