The Science Behind Snoring: How It Happens, and Why It Can Be Dangerous

You snore when the flow of air from your mouth or nose to your lungs makes the tissues of the airway vibrate. This usually is caused by a blockage (obstruction) or narrowing in the nose, mouth, or throat (airway).

When you inhale during sleep, air enters the mouth or nose and passes across the soft palate (the back of the roof of the mouth) on its way to the lungs. The back of the mouth—where the tongue and upper throat meet the soft palate and uvula—is collapsible. If this area collapses, the airway becomes narrow or blocked. The narrowed or blocked passage disturbs the airflow, which causes the soft palate and uvula to vibrate and knock against the back of the throat, causing snoring. The tonsils and adenoids may also vibrate. The narrower the airway is, the more the tissue vibrates, and the louder the snoring is.

See pictures of the tonsils, adenoids, and uvula and the soft palate .

You do not snore when you are awake because the muscles of the throat hold the tissues in the back of the mouth in place. When you sleep, the muscles relax, allowing the tissues to collapse.

Snoring may be caused by:

• Enlarged tissues in the nose, mouth, or throat. Enlarged tonsils are a frequent cause of snoring in children.
• Blocked nasal passages, which make it more difficult to inhale. This affects the tissue of the throat, which may pull together during the extra effort it takes to breathe, which in turn narrows the airway. A blocked nasal passage can be caused by an upper respiratory infection (such as a cold), an allergy, or nasal polyps.
• A deviated nasal septum , which disturbs airflow in the nose.
• Loss of muscle tone in the throat, which makes it easier for tissue to collapse. This can be due to aging or lack of fitness.

Other things that may contribute to snoring include:

• Drinking alcohol, which depresses the part of the brain that regulates breathing. This can overly relax the tongue and throat muscles, causing them to partially block air movement.
• Obesity. Fat in the throat may narrow the airway.
• Medicines that relax you or make you drowsy, such as those taken for allergies, depression, or anxiety.

Snoring occurs when the flow of air from the mouth or nose to your lungs makes the tissues of the airway vibrate. This usually is caused by a blockage (obstruction) or narrowing in the nose, mouth, or throat (airway).

When you inhale during sleep, air enters the mouth or nose and passes across the soft palate (the back of the roof of the mouth) on its way to the lungs. The back of the mouth—where the tongue and upper throat meet the soft palate and uvula—is collapsible. If this area collapses, the airway becomes narrow or blocked. The narrowed or blocked passage disturbs the airflow, which causes the soft palate and uvula to vibrate and knock against the back of the throat, causing snoring. The tonsils and adenoids may also vibrate. The narrower the airway is, the more the tissue vibrates, and the louder the snoring is.

See pictures of the tonsils, adenoids, and uvula and the soft palate .

You do not snore when you are awake because the muscles of the throat hold the tissues in the back of the mouth in place. When you sleep, the muscles relax, allowing the tissues to collapse.

Snoring can be so loud that it keeps your bed partner awake. You may also have a less restful sleep. Studies show that snoring can result in daytime sleepiness and that the louder you snore, the worse your sleep quality is.¹

Snoring may progress to upper respiratory resistance syndrome or sleep apnea, a serious condition. For more information, see the topic Sleep Apnea.

Factors that may increase your risk of snoring include:

• Being male. Men are more likely to snore than women.
• Age. Snoring is most common in middle-aged people. One study reports that among men, the chance that they will begin snoring increases until 50 to 60 years of age and then decreases.
• Heredity. Snoring may run in families.
• Weight gain and obesity.
• Smoking. Exposing children to tobacco smoke may also increase their risk of snoring.²
• Use of alcohol or sedative medicines.
• Chronic nasal congestion during sleep. This is often caused by colds or allergies.
• Jaw abnormalities, such as a small chin and overbite (class II malocclusion —the upper jaw and teeth overlap the bottom jaw and teeth). This may be an especially important factor in women.