Considered as the most common type of sleep apnea, sleep apnea obstructive occurs when there is a partial or even complete blockage in your upper airway while you sleep. This often occurs when the throat muscles become relaxed causing the tongue or even the fatty tissues to fall back into your airway, thus restricting your breathing. It can also occur with enlarged tonsils and adenoids. At this point, air is prevented from moving beyond the obstruction; hence there is a reduction of blood flowing to the brain. When this happens, the brain signals you to wake up partially in order for you to start breathing again which can disrupt your sleep. This can happen many times during the night, so your sleep will be on and off.