In our modern competitive society, nonrestorative sleep is acquiring an increased significance. The international classification of sleep disorders includes 95 different diagnoses of possible causes for nonrestful sleep [12]. A subgroup with a comparatively high incidence rate is formed by the so-called sleep-related breathing disorders (SRBD; synonyma: sleep disordered breathing (SDB)). These are further divided into disorders with central sleep apnea (CSA), obstructive sleep apnea (OSA), sleep related hypoventilation syndromes, and other SRBDs. OSA syndromes are separated into adult OSA and pediatric OSA. The term upper airway resistance syndrome (UARS) is subsumed under this diagnosis because the pathophysiology does not significantly differ from that of OSA. Primary snoring is included in a different subgroup, namely isolated symptoms, apparently normal variants, and unresolved issues.

Snoring is a respiratory sound generated in the upper airway during sleep; it typically occurs during inspiration. Primary snoring occurs without episodes of apnea or hypoventilation. The intensity of snoring may vary and often will disturb the bed partner’s sleep and even awaken the patient. Primary snoring does not cause symptoms of daytime sleepiness or hypersomnia [13].

In contrast to primary snoring, adult OSA has an adverse effect on the daytime life quality. The most frequent symptoms of OSA are intermittent snoring (94%), daytime sleepiness (78%), and diminished intellectual performance (58%). Further symptoms are personality changes (48%), impotence in men (48%), morning headaches (36%), and enuresis nocturna (30%) [253].

OSA is a widespread disorder affecting up to 10.9% of the male and up to 6.3% of the female population [331, 841]. OSA is associated with serious adverse consequences, such as myocardial infarction [311], stroke [166], hypertension [555], and traffic accidents [737], for the afflicted individuals.

In the case of OSA, an imbalance exists between forces dilating and occluding the pharynx during sleep. The muscle tone supporting the pharyngeal lumen is too low, and the inspiratory suction force and the pressure of the surrounding tissue narrow the pharynx and are situated too high [561, 596]. This disorder occurs only during sleep because of a physiological loss of muscle tone of the pharyngeal muscles in this state. The effects are complete cessation of breathing (apneas) or reduced breathing phases (hypopneas). Both events trigger, if sustained long enough, an emergency situation for the body. The body reacts with a central arousal that disturbs the physiological sleep by a release of catecholamines. The latter lead to a strain upon the cardiovascular system via an increase of the tone of the sympathetic system. However, the frequency of apneas and hypopneas during sleep correlates poorly with daytime symptom severity and impact on quality of life. It is possible for any severity level of OSA to occur with any degree of symptomatic sleepiness and, in cases, with no subjective complaints.