The soft tissues of the mouth vibrate during snoring, but with apnea the tongue and other soft tissues periodically fall back and collapse the airway, sometimes totally, sometimes only partially. In either case breathing stops or becomes very shallow, causing oxygen levels in the blood to fall. Your throat muscles contract as you gasp for air, and breathing starts again. Your bedfellow may wonder if you've stopped breathing altogether. Sleep apnea has only recently come to be regarded as a serious problem.
Women sometimes have it, but it is most common in men and the obese.
Though not everyone who snores has apnea, loud snorers are most likely to have it. Heavy drinking is another risk factor. And, though not all the experts agree about this, there is also some evidence that apnea increases the risk of hypertension and cardiovascular disease. The connection between sleep apnea and high blood pressure, though extensively studied, remains controversial. Breathing stoppage for short periods during the night can cause a temporary rise in blood pressure that may become chronic, some researchers believe.