The purpose of breathing is to take in oxygen so that your cells can produce energy. Remember that cellular respiration formula from biology class?
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
One glucose molecule and 6 oxygen molecules turn into 6 carbon dioxide molecules and 6 water molecules and energy (ATP). In between that input and that output are about 22 magnificently complicated steps, a process that came about in an incredible manner that is beyond a simple evolutionary explanation.(1)
How the process came to be aside, cellular respiration is the reason you have to keep breathing all the time. In order for your body to do anything, you need a constant stream of oxygen. You can’t store much of it for long, so you have to get fresh breaths in order to keep turning that glucose into sweet sweet ATP.
Thankfully, there is a lot of oxygen available in our atmosphere (about 21% by volume), so we don’t even have to breathe particularly efficiently to get enough oxygen. In fact, humans extract only about 25% of the O2 in inhaled air. Some other animals, like fish, have to be way more efficient than that, because ocean water has much less oxygen in it compared to atmospheric air.
The typical human breathing volume is about 500mL, even though our maximum capacity is much larger (3400mL and 4800mL for college-aged women and men respectively). As we age, we do not exhale as fully, and our maximum breath capacity decreases.
But why are we talking so much about respiration?
Because mouth taping is actually about increasing respiration efficiency. It’s supposed to encourage you to breathe through your nose instead of your mouth, which helps the respiratory system take in more oxygen, and is also healthier for other reasons.
Note: In case you haven’t already seen the mouth taping trend, it basically entails wearing a piece of tape over your mouth while you sleep. You wouldn’t do it while you are awake, and the correct way to do it is with a gentle strip over the middle of your lips, not duct taping your entire mouth.
So what is the difference between mouth breathing and nasal breathing?
When you inhale through your nose, the air flows first through a maze of spaces in the nasal cavity, then down the trachea, then into the two branching bronchi which lead into the lungs, then into finer tubes called bronchioles, and finally reaches the air sacs called alveoli. The alveoli contain the respiratory surfaces where the gas exchange occurs and oxygen enters the bloodstream.
If you breathe through your mouth, the nasal cavity is bypassed. This is the only difference between the path of the air when mouth breathing versus nasal breathing. So any benefits of nasal breathing are mostly due to whatever happens in the nasal cavity.
The human nasal cavity is larger than one would think. Our noses are actually huge and hidden inside our heads.
What does the nasal cavity do?
One important function is to warm the air to body temperature and humidify it to almost 100%.(2,3) Warm and humid air protects the respiratory tract from drying out and being irritated. Warmed air helps maintain core body temperature more efficiently. And humid air more easily dissolves in the membranes of the alveoli, enabling more efficient gas exchange.
The nasal cavity also protects us from pathogens in two ways. Firstly, the mucus forms a protective barrier against inhaled pathogens. Secondly, the concentrations of nitric oxide in the nasal cavity are very high due to its production in the paranasal sinuses, and this makes the nasal cavity a sterile environment that prevents growth of pathogens.
Nitric oxide has other purported benefits. It helps to dilate the blood vessels, relaxing the airways and increasing the lungsʼ oxygen-absorbing capacity, and improving circulation and airflow.4 Nobel prize winning pharmacologist Louis Ignarro published a book in 2005 called “No More Heart Disease: How Nitric Oxide Can Prevent - Even Reverse - Heart Disease and Stroke.” He also happens to be a top consultant for the MLM Herbalife, which might cast some doubt on his objectivity, but we haven’t gone deeper down that particular rabbit hole.
There are other potential benefits of nasal breathing being explored, including:
https://www.tiktok.com/@petessleep/video/7338851043062746414
In summary, the most well-established functions of the nasal cavity are warming and humidifying air for more efficient oxygen uptake and providing an additional protective barrier from pathogens. Other benefits are under investigation, with some supported by preliminary evidence and others still mostly anecdotal or theoretical.
However, with breathing efficiency being such a compelling health opportunity and a growing topic of interest, these claims deserve further scrutiny. If something this simple could unlock better health and performance, it’s too good not to investigate.
Despite its surging popularity, there has been surprisingly little research about the efficacy of mouth taping. In fact, we found only four existing experiments where participants wore mouth tape during sleep. These were relatively small (20-50 participants each), and all of them only looked at populations of patients with sleep apnea or asthma.(8, 9, 10, 11)
Table 1: Studies about mouth taping during sleep
So, we’re left wondering, is this mouth taping trend actually doing anything for the general population? In particular, does using mouth tape during sleep improve typical sleep quality, snoring, and attractiveness?
Cosimo Research is organizing the first large study to investigate the benefits of mouth taping in a general population. We will be exploring its effects through a decentralized study, gathering data directly through participants' fitness trackers. We'll announce more information soon, but for now, sign up here to register your interest in participating in this groundbreaking research!
