Obstructive Sleep Apnea Syndrome (OSAS) is characterized by repeated episodes of airway obstruction while sleeping. Upper airway obstruction while sleeping leads to a dramatic decrease in oxygen saturation and to hypoxemia finally, in which consequence the patient rapidly awake. Clinical signs are sleepiness and functional cognitive deficits. The Gold standard therapy is "continuous positive airway pressure" ventilation during sleep. However, the success depends strongly to the patient´s compliance. Surgical treatment is an alternative option, which could be considered if clinical success failed. A comparison of the cognitive function of both therapies is not yet analyzed. The study addresses the question which of this treatment options is favorable regarding cognitive function and outcome.

Obstructive Sleep Apnea Syndrome (OSAS) is characterized by repeated episodes of airway obstruction while sleeping. The "Apnea-hypopnea index" (AHI) defined as events per hour, gives information about the severity of the disease. The American Academy of Sleep Medicine Task Force" defined that more than 5 episodes per hour is strongly suspect for an OSAS disease. Upper airway obstruction while sleeping leads to a dramatic decrease in oxygen saturation and to hypoxemia finally, in which consequence the patient rapidly awake. The prevalence rise with age and about 20% of the population is suspect to a sleep disorder. However about 1-5% of male and about 0,5-2% of female aged adults are affected. Main reason is obesity. Clinical signs are sleepiness and functional cognitive deficits. The Gold standard therapy is "continuous positive airway pressure" ventilation during sleep. However, the success depends strongly to the patient´s compliance. Surgical treatment is an alternative option, which could be considered if clinical success failed. It is notable that the long-term mortality is comparable in both medical treatment options. However, a comparison of the cognitive function of both therapies is not yet analyzed. The study addresses the question which of this treatment options is favorable regarding cognitive function and outcome.

Inclusion Criteria:

* Patients within 30 to 70 years of age both gender.

Exclusion Criteria:

• Patients under 30 years of age or older than 70 years of age.
• Preexisting neurological, neuropsychological deficits or diseases, e.g. cerebral insult or epilepsy.
• Preexisting neurological, neuropsychological medication.
• Preexisting neuromuscular diseases.
• Alcohol - and drug abuse.
• Postoperative complications, pain and time shifts within the test protocol.

Patients recruted at the University Hospital Erlangen prior surgery or conventional treatment.