Why Thumb Sucking and Mouth Breathing Are Airway Signals (Not Bad Habits)

The question isn't always like, how do we stop the habit? It's often, what is this habit trying to tell us? I want that reframe to be very solidified by the end of our time together today. Oral habits are behaviors that involve the structures of the mouth, right? So think tongue, lips, palate, teeth, gums, right? Any of those structures. Common oral habits might include thumb or finger sucking, pacifier or soother use, blanket clothing or, you know, material like fabric sucking, tongue sucking, lip sucking or licking, mouth breathing, nail biting, chewing on non-food objects like they're constantly going into the mouth to chew on, like I think a pen cap or, you know, and I'm not talking about babies who are chewing on or sucking on toys because they're in an exploratory agents age appropriate. I'm talking about beyond that. So anytime a non-food item repeatedly enters the mouth for sucking or chewing, we consider it an oral habit. Now, I also wanna preface this with, you know, when I just gave that toy example, a baby puts a toy in their mouth, they chew, they suck for a couple seconds, they take it out, they keep exploring.

That's one thing.

You know, if they're finding their fingers for the first time, the fingers go and they come out and they don't frequently go back in, fine. But if they're constantly going in, that's what we're talking about here, okay? That clarifying moment, right, where infants do mouth objects as part of normal development— that is how they explore their environment. Mouthing toys briefly and occasionally is expected and typical, okay? So again, just to clarify, we're looking for the, like, when this behavior becomes more of a persistent, repetitive, and purposeful behavior, that's when we know it crosses into that— crosses the line or crosses into a category of being an oral habit. There's 3 things we look at, okay? 3 key factors when we're assessing. 1 is frequency, 2 is duration, and 3 is intensity. So the frequency, how often does the habit occur, right? That's number 1. Number 2, duration, how long does it last each time? Number 3, intensity, how much force or effort is involved, right? How intensely are they sucking that thumb for how long and how often does this happen? You know, frequency, duration, intensity, okay? Let's use thumb sucking as an example because it's quite common. We might ask, like, is the child sucking their thumb occasionally or is it throughout the day? Does it happen only briefly or for really long stretches, like especially before sleep, for example? Is the sucking really gentle or is it intense and it's difficult to, like, interrupt that behavior, right? Because when that, when that habit becomes frequent and it happens for long durations and it's with a high intensity, That's when we're like, okay, we need to hit pause for a second and consider a professional evaluation. One of the most common reasons that we actually see these oral habits like thumb sucking, for example, the reason why we see it develop is to fill a void. When the tongue is not resting up on the palate where it belongs, children often substitute with a thumb, a finger, or a pacifier. That tongue is not resting up on the palate where it belongs. Children will substitute with their thumb or a pacifier. And that habit provides sensory input, right? Stability to the jaw and the oral structures. And sometimes it actually even improves the airflow. Many young children who suck their thumb, that thumb is acting like a mandibular advancement device, right? When the thumb sits in the mouth, I'm gonna show you again if you're watching, it gently brings the lower jaw forward a little bit, even just a just a few millimeters. That small shift can open our airway and make breathing easier during sleep. Okay, so the habit isn't random, it's compensatory. And if the airway is restricted due to the jaw position, our high palate, maybe enlarged tonsils or adenoids, maybe poor tongue posture— the posture of the tongue is low, maybe forward, right? The body finds a workaround. Our body is very smart, and that workaround, my friends, often becomes an oral habit.

Tongue up, teeth together, lips closed, breathe through your nose We need to be using our myo superpowers regardless of what our age is. Literally should be happening from birth. Once that nasal airway clears from all of the stuff, you know, coming out of the birth canal and out of the womb. And, you know, yes, babies do take time to clear like that. Those lips should be together. We should have the tongue on the palate. We should be nasal breathing literally from birth.

The tip of the tongue should be gently behind the upper front teeth, like not pushing on those teeth, just like 2 mil, like 1 to 2 millimeters behind. Our lips should be closed. We should be breathing through our nose, right? And that's at every age. Every age. Mouth breathing, my friends, in toddlers isn't just an aesthetic habit. It's a functional signal really in anybody at any age. But let's, we're gonna focus on toddlers a bit.

Okay?

The under 5 crowd. And this can ripple into feeding development, chewing, swallowing coordination, sleep, sleep quality, and craniofacial growth. So today I'm going to give you my assessment basics for the under-5 crowd. It's number 1. Number 2, what to look for with lip seal, tongue posture in toddlers, and nasal breathing. 3, how this ties directly to feeding struggles. 4, age-appropriate assessment techniques you can do without turning your session into a wrestling match. And 5, my favorite part, the 30-second assessment you can do in basically any setting. Why does mouth breathing even matter? Like, why do we care? It is tied to dentofacial development and malocclusion risk. Okay. There is a strong body of evidence showing associations between mouth breathing and patterns like increased vertical growth tendencies. I'm like, think long face, right? People call it long face syndrome, but like basically those longer, more narrow faces, altered jaw position, and malocclusion patterns. Okay. A 2021 systemic review and meta-analysis in BMC Oral Health found that mouth-breathing children showed measurable differences in craniofacial parameters compared to nasal breathers, right? And then there was a concise 2022 review in Frontiers in Public Health that summarized how mouth breathing, which is often driven by airway obstruction like adenotonsillar hypertrophy, right, and large tonsils, adenoids, is linked with abnormal dental and maxillofacial development and emphasizes the importance of early screening. So here's the thing, right? Mouth breathing shows up in broader developmental outcomes, like not just the mouth, right? So one of the biggest like zoom-out studies, a large population-based cohort paper looked at sleep disorder breathing symptom trajectories from 6 months to 7 years, and they included mouth breathing as a key symptom, okay? And they found associations with later behavioral outcomes at ages 4 and 7. This is in the Journal of Pediatrics. Now that's not a feeding paper, right? But it's a loud reminder that breathing patterns early in life matter, and mouth breathing is often part of a bigger physiologic picture. Okay, feeding, my friends, is a breathing sport. Let's just look at it that way. Feeding requires coordinated neuromuscular function across systems. Okay, um, in the ASHA Practice Portal, that highlights feeding as a complex skill that requires tight coordination of multiple nerves and muscles. Which it is. And okay, infant feeding development research emphasizes the essential importance of coordinating swallow-breathe for safe and efficient intake. Okay, that's in the American Journal of Clinical Nutrition. So if a toddler's default is open mouth posture, the low tongue resting position, poor lip seal development, you know, these 3 things, right? Open mouth posture, low tongue resting position, poor lip seal development, you're often looking at a kid who's working harder just to exist. 30 seconds. Number 1, statue. Tell them to freeze like a statue. Watch them for 5 to 10 seconds while they are standing still. Look for, are their lips parted or sealed? Is their jaw hanging? Is their tongue visible or forward? Is their head forward, you know, posture-wise? Or is it, are the ears nicely over their shoulders? Okay, that's the statue. Now the sniff test, okay, it's very play-based. Smell the flowers. Right? Do 2 to 3 quick sniffs. Ask them to do it, like model it for them, then ask them to do the same thing. Let's smell the flowers. Okay, what I want you to look and listen for. Can they sniff with their lips closed? Or is their mouth hanging open? Do you hear a nasal noise? Like, do you hear signs of congestion, right? Is it, or is it, you know, like, that was really bad. Especially those of you listening, I sounded like a pig, not like a congested child. But anyways. Do they immediately open the mouth to breathe? Right? And then optionally you can look at, like, do like a quick nasal airflow check if you're trained and comfortable. You can do like a visual airflow cue. So it's like watching like condensation on a small mirror. So I have one right here, but basically you can basically just have them breathe out and see if the circles on the mirror are the same size, right? We do that in like a full-blown eval. Do that only if like you're trained and comfortable, okay? Because that again will just support what you're already seeing. But I want to say your clinical observation is often enough to know, like, this is not stable nasal breathing at rest.

And here's the thing, thumb sucking isn't just a behavior, it is often a compensation for something deeper like airway obstruction or poor oral function. Okay, and we're going to talk about why thumb sucking happens, why it's so hard to stop, how airway and oral dysfunction play a role, what we can do with certain tools and therapy, and how we go even deeper inside of Feed the Peeds, the course that I teach, right, to assess and address these cases holistically. Holistically. Okay, thumb sucking, my friends, is not just random. It is a— it's a red flag. And I don't love that word red flag, but I do feel like it's a red flag, and it's, it's a red flag that we all need to be like majorly paying attention to. So I'm just gonna let that term live on here, okay? I want to reframe it for you because it's not just a bad habit. It's often a compensatory behavior from an underdeveloped or a dysfunctional oral system. Okay, an oral system. What do I mean by that?

Like your mouth.

What's happening inside the mouth? Why is there dysfunction in there? Is the mouth underdeveloped? When I say underdeveloped, I'm usually talking about the jaws, the bones, right? Your, your maxilla is your upper jaw. Your mandible is your lower jaw. Are we compensating for that being underdeveloped or dysfunction occurring, which this can all be interrelated. There could be dysfunction occurring because we're underdeveloped, right? So here's what happens. We learn to follow the path of least resistance and figure out a way to self-regulate, which our tongue should be doing for us. If our tongue is able to live in the roof of our mouth and it's up there, it creates endorphins, it feels good. Now, a child can't tell you this, right? We can't even really voice this as adults. But when the tongue is not up there in the roof of the mouth for whatever reason, maybe there's not enough space, maybe there's a tongue tie, maybe there's some other oral dysfunction going on, whatever the case may be, our bodies just find ways to self-regulate, and in goes the thumb for a lot of kids, right? And this happens due to poor airway or tongue posturing, like I was mentioning, right? So this is a major red flag for sleep disorder breathing, sensory dysregulation, or even muscle imbalance, right?

There's research that shows that children with obstructive sleep apnea can score 10 to 16 IQ points lower than their peers without sleep disorder breathing. Yet many children who are diagnosed with ADHD or behavioral concerns have never had a sleep evaluation or an oral airway assessment. Make it make sense. So many parents who ask us about, like, what about bitter nail polish or sprays? What about thumb brace or splint? What about taping the thumb? What about sleep sacks or restraints? These approaches may temporarily block access to the habit, but they do not— they don't address the underlying cause. And in some cases, they actually create new problems, especially when they restrict the movement or the sensory input. Okay, if the body still needs to fill the void, it will simply find another way.

The thumb sucking programs that I used in the beginning of my myo career and that I still see out there, and this is not just like one person, this is multiple, they don't address airway first. If we're actually addressing airway first, hi, like you could do feeding therapy, you could do myofunctional therapy and address airway, and oftentimes the thumb will fall by the wayside.

They won't need it anymore.

So why are we putting kids through these programs that are stressful for them and trying to reduce the stress load to basically say bye-bye to the thumb, to then have them get sick, get stuffy, and the thumb go back in again, right? We're not actually solving the problem. Number one, we need to assess the airway first. Airway is always first in everything I do and everything I teach because it's not just about removing the thumb, it's about giving the body a better, like, functional substitute. I want you to avoid shaming or punishing the child for thumb sucking because, hi, they need to do it. It's actually sustaining their life sometimes. It's keeping their airway open, and we need to breathe to live. So no shaming, no punishing.

The oral habits are not random. They are signals. It's like throwing an SOS sign up, right? When we listen to what that habit is telling us and we treat the underlying cause, that root cause, we can support healthier growth, better sleep, improved feeding, and stronger overall development. Okay, we are quite literally connected from the tip of our tongue to the tip of our toes.

Keep observing, keep asking why, and keep leading with function first. Quick disclaimer. All information, content, and material of this podcast are the opinions of the speakers and serves as the informational purposes only and not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified healthcare provider. That wraps up today's special compilation. My goal with these episodes is to bring together the conversations and the insights that are truly moving the needle in our field right now. Next, whether you're a parent looking for answers or a clinician looking to sharpen your skills, remember that the most important tool you have is your own clinical reasoning. Don't just look at the surface level symptoms. Look at the underlying systems. If today's episode shifted your perspective or gave you a new aha moment, I would love to hear about it. Take a screenshot of you listening, post it to your stories, and tag me @HallieBulkin. You can always find more resources and past episodes over at untetheredpodcast.com. Thanks for tuning in, and I'll see you back here next week on the Untethered podcast.