Obstruction occurs behind the base of the tongue and behind the soft palate, which blocks the airway. When one is sleeping, the brain fails to signal the muscles to keep moving, so you are not able to breathe correctly. The brain only signals partially and that is when these occurrences happen.
When it comes to sleep apnea many people stop breathing, but do not tend to notice unless they fully wake themselves up. One may never really know if they have sleep apnea until a sleep study is done.
In order to be able to treat sleep apnea, the mandibular advancement device is adjusted to the degree necessary for better airway passage. The device is able to provide upper air configuration and is able to prevent collapse by correctly positioning the jaw and tongue.
Mandibular repositioning or advancement devices (MRD/MAD) are the most common devices to be able to treat apnea.