You can find all the information about the causes of snoring here. If the muscle at the base of the tongue falls further back than with snoring, the airway is completely obstructed and air can no longer reach the lungs when you breathe in. This interruption to breathing is called obstructive sleep apnoea, i.e. sleep apnoea that leads to constriction of the airways.
A pause in breathing, or an "apnoea" (from the Greek word apnoeia = no wind), may last for a few seconds up to more than two minutes. In sleep medicine, a pause in breathing that lasts for ten seconds or more is considered an apnoea. The clinical significance of an obstructive apnoea is almost the same for an obstructive hypopnoea. In this case, air does flow through the narrow points but the airflow is reduced by at least 50% and the blood oxygen level is at least 3% lower. A hypopnoea must also last at least 10 seconds to be counted and evaluated as such. Officially, around 3 to 5% of all adult men in Germany suffer from an obstructive sleep apnoea syndrome (OSAS). The actual percentage could be much higher, however, as sleep apnoea remains a grossly under-diagnosed syndrome and even many doctors are still unfamiliar with it or do not take it seriously enough.