Tongue posture and mewing: what the evidence shows

Tongue posture is simply where your tongue sits when you are not eating, drinking or talking. Most people never give it a thought. Then social media got hold of it, renamed it "mewing", and started promising that pressing your tongue to the roof of your mouth would carve you a jawline fit for a film poster. I get asked about it more than I ever expected to, usually by younger lads at the gym in Kitakyushu who have watched one video too many.

Here is the plain version: the normal resting position, what mewing claims, what the research supports, and when to see a dentist, an orthodontist or a doctor rather than another video.

Where a resting tongue usually sits

Dentists, orthodontists and speech and language therapists describe much the same resting position:

• The tip of the tongue rests lightly on the ridge just behind the upper front teeth, not pressing on the teeth themselves.
• The rest of the tongue lies up against the roof of the mouth, without force.
• The lips are closed but not clenched.
• The back teeth are slightly apart. Dentists call this small gap the freeway space, and it is normal. Teeth are meant to meet when you chew and swallow, not all day.
• You breathe through your nose.

You can find the spot in a few seconds. Say the letter N and stop with your tongue where it lands. That ridge behind your top teeth is where the tip of a resting tongue usually sits. Now close your lips, let your back teeth come apart a touch, and breathe through your nose for a minute. If that feels natural, you probably do it already. If it feels like hard work, or your nose will not let enough air through, that is the more useful thing to have learned.

The opposite pattern is often called low tongue posture: the tongue lying on the floor of the mouth, often with the lips a little apart. It usually goes hand in hand with mouth breathing, and for an obvious reason. If your nose is blocked, you need an open airway through the mouth, and a tongue pressed to the palate gets in the way.

Swallowing matters too. A normal adult swallow pushes the tongue up and back against the palate. Pushing it forward against the front teeth instead, called tongue thrust, is common in small children, who mostly grow out of it; in older children it can go with an open bite, where the front teeth do not meet.

Japanese paediatric dentists have a phrase for children whose lips habitually hang open at rest: kuchi pokan, roughly "mouth agape". Since 2018, Japan's national health insurance has covered assessment and training for children whose chewing, swallowing, speech or breathing habits are judged to be developing poorly. Whatever you make of mewing, the dental profession here takes resting mouth posture in children seriously.

Mewing explained

The name comes from John Mew, a British orthodontist who from the 1970s promoted an approach he called orthotropics, later carried on by his son Mike Mew. The idea, broadly, is that modern faces grow longer and narrower than they should because of soft diets, mouth breathing and low tongue posture, and that training the tongue to rest high, with appliances in children, guides the face to grow forward instead. Most orthodontists regard orthotropics as unproven.

Online, this turned into "mewing": flatten the whole tongue against the roof of the mouth, seal the lips and hold it all day. The promises grew with each retelling: a sharper jawline, higher cheekbones, straighter teeth, no double chin, better posture, cured snoring.

What the evidence does and doesn't show

Can tongue posture affect how a child's face grows?

Probably, to a degree. Studies going back decades have linked long-term mouth breathing in childhood, often from large adenoids or tonsils or a nose blocked by allergies, with a longer lower face, a narrow upper jaw and crossbites. The catch is that most of this research is observational. It shows that these things turn up together, not which one causes which, and genes play a large part in face shape. What is missing is good trials showing that teaching children to mew changes how their faces grow. The practical point stands, though: a child who mouth breathes and snores is worth getting checked, for reasons that have nothing to do with looks.

Can mewing change an adult's jawline?

There is no good evidence that it can. By adulthood the facial bones have finished growing, and the seam down the middle of the roof of the mouth has often fused, at least in part, which is why widening an adult upper jaw often needs surgical help. A tongue, however dedicated, is not a known way to reshape a fully grown jaw.

The before-and-after photos have duller explanations. I spent years looking at bodies from every angle, and I can tell you that the angle of the neck changes the look of the jaw more than anything else. Try it in a mirror. Poke your head forward and the jawline softens. Draw your chin back and lengthen the back of your neck and it sharpens. Add a slightly lower camera, better light and a few kilos lost, and you have a convincing thumbnail. That is posture and photography, not bone.

Can it do any harm?

Resting the tongue lightly where it belongs does no harm. Pressing hard all day is a different matter. Some people end up clenching, with tired jaw muscles, headaches around the temples, or a flare-up of jaw joint trouble (temporomandibular disorder, or TMD). Teeth also move under gentle, steady pressure, which is exactly how braces work, so a tongue that pushes against the front teeth for hours is not a neutral habit. If you wear braces or a retainer, ask your orthodontist before trying anything.

A related trend called "bone smashing", where people tap their faces with hard objects in the hope of building bone, deserves one sentence: please do not hit your face with things.

Does tongue posture fix neck posture?

Mouth breathing and a forward head posture often show up together, partly because pushing the head forward opens the airway a little. A few small studies have found links between them. Nobody has shown that changing where your tongue rests will straighten your neck. If your neck and shoulders are the real complaint, my guide on how to fix your posture covers what does help: moving more often, strengthening the upper back and sorting out your screen. A clenched jaw also feeds into the stiff shoulders I described in the piece on katakori, so easing off the pressure in your mouth can help there.

What about snoring and sleep apnoea?

Here there is something better than hearsay. Orofacial myofunctional therapy is a set of exercises for the tongue, lips and throat, taught by trained therapists. Small trials and reviews suggest it can reduce snoring and help some adults with mild to moderate obstructive sleep apnoea, usually alongside standard treatment rather than instead of it. The example I like most is a Swiss trial published in the BMJ which found that learning the didgeridoo reduced daytime sleepiness in people with moderate sleep apnoea. I mention it partly because it is real research and partly because I like picturing the practice sessions.

None of this replaces a diagnosis. Sleep apnoea is common and treatable, and it needs a proper sleep study, not a jaw exercise found on a phone.

Mouth taping, sticking the lips shut at night, is the other trend in this corner. The evidence is thin, and it is a poor idea if your nose is often blocked or if you might have sleep apnoea, because it can hide the very snoring that should send you to a doctor.

A sensible way to try it

If you want to work on your resting tongue, do it gently:

1. Check your nose first. Sit with your mouth closed and breathe through your nose for two minutes. If you cannot, that is the thing to sort out. Plenty of people in Kyushu breathe through their mouths for the whole of the spring cedar pollen season, and hay fever, a deviated septum, nasal polyps or large adenoids are all worth a doctor's look. In Japan you can usually walk into an ear, nose and throat clinic (jibika) without a referral.
2. Find the spot with the N sound.
3. Rest, do not press. The tongue lies against the palate as lightly as your hand rests on a table. Lips closed, back teeth apart.
4. Check in through the day: at a red light, while the kettle boils, at the end of each email. Habits shift through repetition, not force.
5. Notice your swallow. With lips closed, the tongue should go up and back, not forward against the teeth.
6. Stop if your jaw aches or you start getting headaches.

You may also meet a-i-u-be, a mouth exercise popular in Japan: exaggerate each sound, then stick your tongue out and down on "be". It is meant to encourage closed lips and nose breathing. The research is limited, but it is harmless and children find it funny.

When to see a dentist, orthodontist or doctor

• Loud snoring, pauses in breathing that someone else has noticed, waking with a gasp or a choking feeling, morning headaches or sleepiness through the day. See your GP or family doctor about sleep apnoea. If you have nodded off at the wheel, stop driving until you have been checked. The NHS has clear information on the signs. Treatment may be a CPAP machine or a mouthpiece made by a dentist after diagnosis.
• A child who snores most nights, breathes through the mouth, sleeps restlessly, wets the bed again after being dry, or struggles with tiredness or concentration in the day. Start with a GP or paediatrician; large tonsils or adenoids are a common cause.
• A child with crowded or protruding teeth, a crossbite or front teeth that do not meet. A dentist can say whether an orthodontic opinion is worth having while the jaws are still growing.
• Jaw pain, clicking with pain, a jaw that catches or will not open fully, or pain when chewing. See a dentist or doctor. Most jaw joint problems settle with simple measures, but they are worth having looked at.
• Jaw, neck or arm pain with chest pain, breathlessness, sweating or nausea. Call an ambulance (119 in Japan, 999 in the UK) straight away.
• New pain in the jaw when chewing, with headache, a tender scalp or changes in vision, especially over the age of 50. Get seen the same day.
• A jaw locked open or shut, facial swelling with fever, or difficulty swallowing or breathing need urgent care.
• Numbness of the face or tongue, a lump in the neck, or a mouth ulcer that has not healed within three weeks. See a dentist or doctor promptly.
• Neck pain with numbness, tingling or weakness in the arms, pain after a fall, or pain that wakes you at night.
• Speech that worries you, such as a lisp in an older child, or feeding problems in a baby. A speech and language therapist or health visitor is the right person, and a baby may need checking for tongue-tie.

The one thing to take away

If you want to do something with your tongue, start with your nose. Comfortable nose breathing, lips closed, tongue resting lightly up top and teeth apart is a decent habit with no downside. A new jawline is not on offer. A good night's sleep, if snoring is the real problem, may well be, and that starts with a doctor.