The first stage, Sleep A, is the process of going to sleep with Sleep B, or Alpha-Beta Sleep, accounting for about 50 percent of the average sleep cycle, Wiebelhaus said. During that resting phase, the individual can detect the phone ringing or other distractions. It helps you feel rested but it really isn't doing anything for your body. In a typical night's sleep, the individual moves next into deep sleep when the mind sleeps and the subconscious takes over. Such sleep consumes only about 10 percent of a night's sleep and occurs in the first half of the night, Wiebelhaus said.
Sleep apnea is detected in REM sleep.
Named for the Rapid Eye Movement caused by eyes reacting to dreaming, this phase marks the body at rest. During an average night sleep, a person will pass between REM and Sleep B six to eight times. During this physically rejuvenating REM cycle, the individual loses all muscle tone. Basically the patient is suffocating. They wake up with this loud snorting arousal.