Snoring is an inspiratory noise caused by vibration of soft palate and posterior faucial pillars. Snoring corresponds to partial obstruction of upper airway, and complete obstruction is followed by an apnea. Heavy snoring is practically always present in obstructive sleep apnea syndrome.
Upper airway resistance syndrome (UARS) was first used by Guilleminault and colleagues to describe a subgroup of patients with conditions that were formerly diagnosed as idiopathic hypersomnia or CNS hypersomnia.
These terms used to describe excessive daytime sleepiness without a cause that was clearly defined by a nocturnal polysomnogram or the multiple sleep latency test. The clinical importance of snoring and UARS is reviewed in this article.