Disclaimer: I am not a registered dietitian, naturopath, doctor, or other type of healthcare professional. This is simply the product of my own research and opinions, not to be used to replace the recommendations of a registered healthcare provider.
I have a confession: I was (and sometimes still am) a mouth breather. Other than the negative connotation that mouth breathers are slow and unintelligent, standing around slack-jawed all the time, I didn’t think that there was anything ~actually~ wrong with mouth breathing. Humans have the capacity to breathe out of both our nose and our mouth; and I honestly thought that we could just pick whichever one is easier for us. Not only did I mouth breathe during the day, but my mouth breathing was even more aggressive at night, where I would regularly fall into a deep sleep with my mouth wide open.
For most of my life, I never thought that this was an issue. However, later on in my life, I started to notice that I had a lot of the same recurring symptoms: I was always thirsty no matter how much water I drank, I always had a dry mouth (making me feel thirstier), and no matter how much I slept at night I would always wake up tired. Previously, I thought that these symptoms meant that I had to drink more water and make more of an effort to tire myself out during the day (with more exercise) in order to get a more restful sleep at night.
Then, one day, one of my best friends told me that her boyfriend, who plays hockey, went to a functional medicine doctor, and the doctor told him that if he ever wants to play hockey professionally he needs to stop mouth breathing. A couple of months later, my boyfriend called me one day telling me that he listened to an audiobook called “Breath” by James Nestor; and he said that mouth breathing is a very bad habit. About a month after that, I was listening to a functional medicine podcast called Dr. Ruscio radio; and he had a guest saying that mouth breathing, specifically nocturnal mouth breathing (mouth breathing at night), is bad for your health.
My whole life I had never heard anything against mouth breathing, and now within the span of two months I have been bombarded with information saying that mouth breathing is no longer nose breathing’s innocent cousin. Is mouth breathing really that bad? After doing my own search of the recent literature, I have found the following conclusions:
1. Children who mouth breathe had a higher rate of altered neck posture – typically a forward head posture to facilitate air going into the mouth - and decreased respiratory muscle strength compared to nose breathing children [1,2]
2. In the long run, the hyperactivity of the neck muscles while mouth breathing may be associated with cervical changes that can cause jaw and cervical spine disorders; as well as a deterioration in pulmonary function 
3. Symptoms of mouth breathing commonly include sleeping with mouth open, snoring, nasal itching, nocturnal breathing difficulty or restless sleep, nasal obstruction, daytime sleepiness, headache, and irritability during the day 
4. Respiratory biomechanics and exercise capacity were negatively affected by mouth breathing [2,3,5]
5. Mouth breathing in late adolescence shows a significantly higher plaque index and risk of tooth decay relative to nose breathing 
6. Mouth breathing is perpetuated by decreased activity of the diaphragm and weakening of the abdominal musculature, requiring a higher level of activity from the accessory musculature for inspiration – leading to increased energy consumption and improper lung ventilation [5,2]
Overall, the data reliably concluded that there are significant differences between head and neck posture and respiratory biomechanics in individuals who mouth breathe compared to individuals that nose breathe. Because the primary muscles used for ventilation, namely the diaphragm and the abdominals, are used less in mouth breathers, this requires more activity from the accessory muscles and more energy for ventilation. This can lead to reduced exercise capacity and decreased lung function in the long run, because it requires significantly more energy for a mouth breather to breathe compared to a nose breather. Lastly, the abnormal head and neck posture can, later on, result in jaw and cervical spine disorders. Thus, it is evident from this research that mouth breathing is not simply “another breathing option”, but rather an abnormal breathing pattern that should be corrected to ensure proper posture, muscle tone, improved oral health, increased exercise capacity, and proper lung function.
So, how do you kick the mouth breathing habit? It’s definitely not going to happen overnight, especially if you’ve been breathing this way for most of your life, but here are some of the things I started doing to make the switch from mouth breathing to nose breathing:
3 Main Things I’ve Started Doing to Stop Mouth Breathing
1. Taping my mouth shut at night
For the past month or so, I’ve started taping my mouth shut before I go to sleep. Because it’s impossible to be mindful of your breathing while you’re sleeping, taping your mouth pretty much forces you to breathe out of your nose all night. Doing this sounds really silly, but I was shocked the first time I did it at how much more energized I felt waking up in the morning. If I miss a night, I definitely notice it the next morning both in my level of tiredness and by how dry my mouth is in the morning. I’ve used a couple of brands so far, but my favourite one is Nexcare Sensitive Skin Tape because it is inexpensive and stays on all night – but is also gentle enough that I’m not waxing my upper lip every morning.
2. Being more mindful of my breathing during the day
This one is the most difficult because breathing is something we typically don’t pay attention to throughout the day. However, I usually try and remind myself to check in on my breathing at least a few times a day. Over time, I have started to get better at “catching” myself mouth breathing and start breathing through my nose instead. I also notice that if my mouth is dryer than usual and I’m thirstier, that that’s probably evidence that I have been mouth breathing for the past little while.
Meditating is a great opportunity to work on breathing through your nose because this is most likely the one time in your day where you are focusing exclusively on your breathing and bringing awareness to your body. During the day, you’re thinking about the homework you have to do, work tomorrow, the laundry, what you’re going to have for dinner, and so on; and little attention is paid to your breath. Therefore, scheduling a set amount of time dedicated to working on your breathing each day will help your new habit stick both in and outside of your meditation time. Additionally, meditating is a time when I am also more aware of my posture, where the proper alignment of the head and neck facilitates nose breathing.
Do you ever mouth breathe? Let me know in the comments!
 Okuro, R. T., Morcillo, A. M., Sakano, E., Schivinski, C. I., Ribeiro, M. Â, & Ribeiro, J. D. (2011). Exercise capacity, respiratory mechanics and posture in mouth breathers. Brazilian Journal of Otorhinolaryngology, 77(5), 656-662. doi:10.1590/s1808-86942011000500020
 Veron, H. L., Antunes, A. G., Milanesi, J. D., & Corrêa, E. C. (2016). Implicações da respiração oral na função pulmonar e músculos respiratórios. Revista CEFAC, 18(1), 242-251. doi:10.1590/1982-0216201618111915
 Okuro, R. T., Mocillo, A. M., Ribeiro, M. A., Sakano, E., Conti, P. B., & Ribeiro, J. D. (2011). Mouth breathing and forward head posture: effects on respiratory biomechanics and exercise capacity in children. J Bras Pneumol, 37(4), 471-479.
 Mummolo, S., Nota, A., Caruso, S., Quinzi, V., Marchetti, E., & Marzo, G. (2018). Salivary Markers and Microbial Flora in Mouth Breathing Late Adolescents. BioMed research international, 2018, 8687608. https://doi.org/10.1155/2018/8687608
 Corrêa, E. C., & Bérzin, F. (2008). Mouth Breathing Syndrome: Cervical muscles recruitment during nasal inspiration before and after respiratory and postural exercises on Swiss Ball. International Journal of Pediatric Otorhinolaryngology, 72(9), 1335-1343. doi:10.1016/j.ijporl.2008.05.012