is a term that describes a broad continuum of breathing abnormalities that occur during sleep. On one end of the spectrum, mild narrowing and/or laxity of the airway tissues may first present as snoring. This is sometimes termed “benign snoring” because it does not cause sleep disturbances. However, snoring alone may increase a patient’s risk for stroke, so it is difficult to know for certain if any amount of snoring is “benign.” Next on the continuum is upper airway resistance syndrome (UARS). This occurs when the narrowing of the airway causes increased effort to breathe. This phenomenon can cause poor sleep quality, morning headaches, insomnia, and mood disturbances, among other problems. It is important to note that not all patients with UARS snore and not all patients even realize they sleep poorly. It is possible to be asleep the whole night, but not get into deeper, more restorative sleep because the body is fighting to keep the airway open. When the airway narrows to a point that oxygen saturation in the body is significantly affected, the patient has obstructive sleep apnea-hypopnea syndrome (OSAHS). A hypopnea is a partial narrowing of the airway for a minimum time associated with a certain oxygen saturation drop. An apnea is a complete or almost complete blockage of the airway for a certain time.