Central hypoventilation is like having a long central hypopnea. This event is usually indicated with reduction in both airflow and effort. A second type of breathing event is called "upper airway resistance syndrome," (UARS) which is like having a long obstructive hypopnea. This event is usually indicated by a decrease in the airflow with an increase in effort, and is often associated with snoring. Both events seem to last from the time the patient goes to sleep until they either awaken, have an arousal, suffer a decrease in oxygen levels, or have a heart rate event. It is not unusual to find both central hypoventilation and UARS together.