What Causes Snoring? The Science and Risk Factors Explained

Snoring is the hoarse or harsh sound that occurs when air flows past relaxed tissues in your throat, causing those tissues to vibrate as you breathe.^[1] In other words, the noise isn’t coming from your voice box — it’s the soft, floppy parts of your upper airway fluttering like a flag in the wind.

If you (or the person next to you) snore, you’re in very good company: about half of adults snore at least occasionally, and roughly a quarter to two-fifths of men and one-tenth to a quarter of women snore habitually.^[5] But why it happens varies from person to person, and understanding your own causes is the first step towards fixing it — because the right remedy depends on the reason.

The physiology: why relaxed tissue makes noise

When you’re awake, the muscles of your throat — the pharyngeal dilator muscles — actively hold your airway open. Snoring requires the sleep-induced relaxation of these muscles: once they slacken, the airway narrows, and when the dilators fail to keep it fully open, air has to move faster through the smaller space. That faster airflow makes the surrounding soft tissue flutter, producing the raspy noise of snoring.^[2]

This is why you snore asleep but not awake. As you doze off, the soft palate (the fleshy back part of the roof of your mouth), the tongue and the throat muscles all relax. The more the airway narrows, the more forceful the airflow becomes — and the louder the snoring gets.^[1]

Which tissue does the vibrating? A 2018 systematic review confirmed that the soft palate and the uvula — the small teardrop of tissue hanging at the back of your throat — are the key vibrating structures in most snorers.^[4] The NHS puts it simply: snoring is caused by the tongue, mouth, throat or airways in the nose vibrating as you breathe, because these parts relax and narrow during sleep.^[3]

Where the sound comes from: nose, mouth or throat

The sound can originate from the nose, the mouth, or both, and it typically occurs on the in-breath — though it can happen in any stage of sleep.^[5] Broadly:

• Nose: congestion, a deviated septum or nasal polyps restrict airflow before it even reaches the throat, forcing harder breathing through a narrower channel.^[1][6]
• Throat (the most common source): the soft palate and uvula flutter in the nasopharynx — the space where the back of the nose meets the throat.^[2]
• Mouth and tongue: a large tongue or poor muscle tone allows tissue to fall back into the airway, especially when lying face-up.^[6]

Working out your source matters, because remedies are site-specific: nasal strips and dilators help nasal snorers but do little for palatal snoring, while mouth and throat exercises target tongue and throat muscle tone.

The major risk factors — and the evidence behind them

Excess weight — the most common cause

ENT UK ranks being overweight as the most common contributor to snoring.^[7] Extra tissue around the pharynx narrows the airway from the outside in,^[1] and neck circumference above 17 inches in men or 16 inches in women is a major risk factor for obstructive sleep apnoea.^[9]

The strongest evidence comes from the Wisconsin Sleep Cohort, a study of 690 adults published in JAMA in 2000. A 10% weight gain predicted roughly a 32% increase in the apnoea-hypopnoea index (AHI — the number of breathing disturbances per hour of sleep) and a six-fold increase in the odds of developing moderate-to-severe sleep-disordered breathing (95% CI 2.2–17.0). Encouragingly, it works in reverse: a 10% weight loss predicted roughly a 26% decrease in AHI.^[8] That makes weight one of the most powerful lifestyle levers available.

Alcohol before bed

Alcohol relaxes the very throat muscles that are supposed to keep your airway open.^[1] A 2018 meta-analysis of 21 studies found that higher alcohol consumption was associated with a 25% increase in sleep apnoea risk (relative risk 1.25, 95% CI 1.13–1.38).^[10]

Smoking

A 2023 meta-analysis of 13 studies found that smokers had higher AHI scores and worse blood-oxygen levels during sleep; smoking was associated with severe obstructive sleep apnoea, with a dose-dependent effect at 20 pack-years or more.^[11] There is good news for quitters: in one analysis, ex-smokers’ snoring declined to the level of never-smokers within four years of stopping.^[12]

Nasal obstruction

A blocked nose forces faster, more turbulent airflow. In the Wisconsin cohort, people with chronic night-time rhinitis (a persistently runny or congested nose) had twice the odds of habitual snoring (OR 2.0), and those with allergic congestion were 1.8 times more likely to have moderate-to-severe sleep-disordered breathing.^[13] Structural problems — a deviated septum or nasal polyps — have the same narrowing effect.^[1][6]

Sleeping on your back

When you lie face-up, gravity pulls the tongue and soft tissues down and backwards, narrowing the airway.^[12] This is why many people snore only, or mostly, on their back — and why positional therapy can be remarkably effective for the right person.

Age

Muscle tone throughout the body decreases with age, including in the throat, so airways sag and narrow more readily during sleep.^[14] Interestingly, the pattern isn’t a straight line for ever: men become less likely to snore after the age of 70.^[5]

Male sex

Men are consistently more likely to snore — ENT UK estimates around three times more likely than women.^[7] Habitual snoring affects roughly 40% of adult men versus 24% of adult women.^[5]

Menopause

Women’s risk changes sharply at menopause. In a large study published in 2001, sleep apnoea prevalence was 0.6% in premenopausal women but 2.7% in postmenopausal women not taking hormone replacement therapy — while postmenopausal women on HRT had a prevalence of 0.5%, similar to premenopausal levels.^[15] We cover this in depth in our guide to snoring in women.

Anatomy

Some people are simply built to snore: a low, thick soft palate, an elongated uvula, enlarged tonsils or adenoids, a large tongue, extra pharyngeal tissue, or a deviated septum all narrow the airway.^[1][6] A family history of snoring is itself a recognised risk factor.^[1]

Sedatives and sleeping pills

Sedative medications relax airway muscles much as alcohol does.^[14] The NHS specifically advises snorers not to take sleeping pills.^[3]

Sleep deprivation

Not getting enough sleep is itself a risk factor for snoring^[1] — likely a vicious circle for people whose snoring already fragments their nights.

Pregnancy and hypothyroidism

Pregnancy — especially the final month — and an underactive thyroid (hypothyroidism) are both associated with snoring.^[16][12] Pregnancy hormones and weight changes contribute to airway narrowing.^[14]

Risk factors at a glance

What to do next

Most of the heaviest-hitting causes — weight, alcohol, smoking, sleeping position, sedatives — are things you can change, and evidence-backed remedies exist for the rest. Our complete guide to how to stop snoring walks through every option, matched to the cause.