The noisy sounds of snoring occur when there is an obstruction to the free flow of air through the passages at the back of the mouth and nose. This is the collapsible part of the airway where the tongue and upper throat meet the soft palate and the uvula (the fleshy structure that dangles from the roof of the mouth back into the throat). When these structures strike against each other and vibrate during breathing - that is snoring. Persons who snore have at least one of the following problems:

	Poor muscle tone in the muscles of the tongue and throat which allows the tongue to fall back into the airway. This occurs when the person's muscle control is too relaxed, possible from alcohol or other drugs which cause sleepiness. It also happens to some persons when they relax into the deep stages of sleep.
	Excessive bulkiness of the tissues of the throat. Large tonsils and adenoids can cause snoring in children. Overweight persons also have bulky tissues in their neck. Cysts or tumors could be present, but these are rare.
	Excessive length of the soft palate and uvula It may dangle into the person's airway and act as a flutter valve during relaxed breathing and contribute to the noise of snoring.
	Obstructed nasal passages. When a person has a stuffy or blocked-up nose he must blow hard to inhale air through it. This creates an exaggerated vacuum in his throat; the collapsible part of the airway then pulls together with the floppy tissues of the throat. Snoring then occurs in persons who would not snore if they could breathe properly through their nose. This explains why some people snore during hay fever season or when they have a cold or sinus infection. Deformities of the nose or nasal septum may also cause such an obstruction. Deviated septum is a common term for the deformity of the wall inside the nose that separates one nostril from the other.