The cycle of OSA starts with snoring. The airway collapses or closes off. The person tries to breathe but is unable to get air into their lungs through the collapsed airway and an apnea (cessation of breathing) occurs. The brain realizes that it is not getting enough oxygen and fresh air and it wakes the person from a deep level, to a lighter level, of sleep. The airway then opens and normal breathing resumes. The person falls back into a deeper sleep, begins snoring again and the cycle repeats.