How snoring happens: the anatomy and physics of a snore

Snoring happens when the soft tissues of your upper airway relax during sleep, the airway narrows, and the air you breathe in makes those loose tissues vibrate. The soft palate and uvula at the back of the roof of your mouth are the usual source of the sound, but the throat walls, tonsils and tongue base can join in. Anything that narrows the airway further, from a stuffy nose to a glass of wine, makes the vibration more likely.

For a list of everyday causes and what to try for each, see 10 reasons you snore. This article is about the mechanics underneath them.

How does snoring happen?

Snoring happens because the parts of your airway that are firm while you're awake go slack when you sleep. The NHS explains that snoring is caused by your tongue, mouth, throat or the airways in your nose vibrating as you breathe, and that it happens because these parts relax and narrow when you're asleep.

Cleveland Clinic's sleep specialist Dr. Nancy Foldvary-Schaefer puts it simply: snoring is caused by the muscles that support your upper airway getting weak and floppy at night, and the snore is "the sound your airway makes when it's unstable."

A 2010 review of snoring acoustics in Sleep Medicine Reviews describes the core mechanism as vibration of structures in the throat. It adds that natural or drug-induced sleep is required for snoring to appear. Awake, your muscles hold the same tissues firmly enough that air passes without setting them moving.

What is the physics behind the sound?

The physics is about airflow through a narrowed, floppy tube. A 2024 systematic review in the Journal of Personalized Medicine explains that snoring typically arises when you breathe in, because resistance in the upper airway increases during sleep. As the airway narrows, resistance rises, and that leads to vibration and the characteristic sound.

You can see the size of that change in a 1997 study that measured resistance to breathing in. In young men who didn't snore, resistance rose by 70% from waking to stage 2 sleep. In habitual snorers, it rose by 280%. Awake, both groups had the same resistance. Asleep, the snorers' airways became far harder to pull air through. The authors noted that greater effort to breathe against higher resistance increases the tendency of an unstable airway to collapse.

The German snoring guideline, using international diagnostic criteria, describes snoring as generally a breathing-in sound, which fits with that rise in resistance on the in-breath. Sounds on the out-breath happen too, and our guide to what different snoring sounds mean covers those.

The pitch of a snore depends on what's vibrating. The 2010 acoustics review says flutter of the soft palate gives snoring its harsh quality, with a low pitch (under 500 Hz) and a regular pattern of harmonics. Snoring from other parts of the throat is more noise-like, with its energy spread into higher frequencies.

Which parts of the airway vibrate when you snore?

The parts of the airway that vibrate when you snore are mostly in the throat, with the soft palate the most common source. A German guideline on snoring in adults calls the oropharynx, the part of the throat behind the mouth, a favored site for snoring noises because of its slight tendency to collapse. A 2017 study used a camera to watch the throats of snorers during drug-induced sleep while recording their snores, and identified three vibrating sources: the palate, the side walls of the throat, and both together.

The soft palate gets the most attention. Cleveland Clinic explains that if the roof of your mouth is longer or softer than usual, or your uvula is longer, the opening from your nose to your throat is narrower, and these tissues can vibrate and bump against each other as you breathe. The 2024 review agrees that snoring commonly comes from the soft palate or uvula, and that a long or floppy soft palate can vibrate as air passes.

The tongue matters most when you're on your back. Cleveland Clinic says that position can let your tongue relax toward the back of your throat, partly blocking the airway. The NHS matches a tongue partly blocking the back of the throat to a mouthpiece that brings the tongue forward.

Anatomy sets the stage too. Cleveland Clinic lists enlarged adenoids, big tonsils and a large tongue as features that can restrict airflow.

What role does the nose play?

The nose plays a supporting role rather than making the noise itself. The German guideline says vibration inside the nose generally isn't possible because the nasal skeleton is too stable. But it adds that impaired nasal breathing can be a co-factor in snoring elsewhere, such as at the soft palate.

Cleveland Clinic explains how. When your nasal passages are partly blocked, you have to make an extra effort to move air through them, and that can pull together or collapse the soft, dangling tissue in your throat. It names a deviated septum and nasal polyps as structural causes of that kind of blockage, and colds and allergies as temporary ones. The 2010 acoustics review lists the route of breathing, nose or mouth, among the things that influence snoring.

That's why opening the nose can quiet snoring for some people even though the sound doesn't come from there. Our guide to how nasal strips work explains the mechanics of lifting the nostrils open.

How does sleep stage change snoring?

Sleep stage changes snoring because muscle tone shifts as you move through the night. The National Heart, Lung, and Blood Institute (NHLBI) explains that you cycle between non-REM and REM sleep every 80 to 100 minutes, and that during REM sleep your muscles normally go limp.

You might expect REM sleep to be the loudest, but one study found the opposite. In a 2003 sleep lab study of 72 habitual snorers, snoring increased in deeper non-REM sleep and decreased in REM sleep in any given position. Snoring is clearly tied to sleep stage, but the pattern isn't as simple as "more relaxed means louder." Our article on whether snoring means deep sleep looks at this in more detail, and sleep stages explained covers the cycle itself.

Why is snoring louder some nights?

Snoring is louder some nights because the things that relax or narrow your airway change from night to night. The 2010 acoustics review notes that snoring can vary within a single night and between nights, and is influenced by body position, sleep stage and the route of breathing.

The common night-to-night triggers are well known. Cleveland Clinic says alcohol, sedatives and even lack of sleep can relax the muscles in your upper airway, and that congestion from allergies and colds can block airflow. In the 1997 resistance study, a bedtime dose of vodka more than doubled the rise in airway resistance from waking to sleep, in snorers and non-snorers alike. Our article on alcohol and snoring covers that link.

Position is the other big variable. The 2003 sleep lab study found that most snorers without sleep apnea snored less often and less loudly on their side than on their back. A night spent mostly on your back can sound very different from one spent on your side. See sleep position and snoring.

Longer-term changes add up too. Cleveland Clinic says snoring becomes more common with age as muscle tone decreases and the airways narrow, and that it's more common in people with overweight or obesity.

When does snoring point to something more?

Snoring points to something more when the airway doesn't just vibrate but closes. The NHS says to see a GP if you feel sleepy during the day, your breathing stops and starts while you sleep, or you make gasping or choking noises, since these can be signs of sleep apnea. Cleveland Clinic says loud, disruptive snoring is more likely to come with sleep apnea and is worth discussing with a provider. Our guide to snoring vs. sleep apnea explains the difference.

What can you do with this?

Knowing where your snore comes from helps you pick the right fix. If your nose is the trigger, opening it up comes first. If your mouth falls open and your nose is clear, keeping your lips closed keeps breathing on the nasal route, which the acoustics review lists among the factors that shape snoring. Check your nose with our nose test before you try mouth tape. We don't recommend mouth tape for children.

Our pick (paid partner): Titan Sleep System

For snoring that seems to start with a stuffy nose or an open mouth, our pick is the Titan Sleep System. Titan says it brings TitanAir Nasal Strips and Titan Mouth Tape together as one nightly system.

Titan describes the strips as drug-free external nasal dilators with flexible spring-loaded bands, and the tape as a bamboo silk strip worn across the lips. Titan says every batch is third-party tested and certified PFAS-free, and it refunds you if your sleep isn't better after 30 nights. We haven't tested or ranked these products ourselves; this is our recommendation for ordinary snoring, not for anyone with signs of sleep apnea.

Read next

• 10 reasons you snore, and what to try for each
• What different snoring sounds mean
• How to stop snoring

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.