Effect of nasal or oral breathing route on upper airway resistance during sleep -Fitzpatrick et al. (2003)

Key Points

  • Mouth breathing during sleep significantly increases upper airway resistance compared to nasal breathing

  • Mouth breathing also is associated with a significant increase in obstructive sleep apnea when compared to nasal breathing

  • Nasal breathing is the preferred route for breathing during sleep in healthy adults

The Breathing Diabetic Summary

If you can’t tell by now, I’m a huge fan of nasal breathing.  In fact, the most significant thing I have ever done for my health is switch to nose breathing at night (by taping my mouth shut).  This paper helps explain why.

The authors had conducted a previous study that examined how people naturally breathe at night.  The results showed that healthy individuals breathed almost exclusively through the nose during sleep (that definitely wasn’t the case for me!).  So, they wanted to see if there was a mechanical advantage to nose breathing versus mouth breathing during sleep.

They had 12 subjects spend the night at a sleep hospital.  They had the participants sleep with a mask that allowed the scientists to control whether they could breathe through their nose or mouth.  During part of the night, they were forced to breathe through their nose, and during another part through their mouth.  They continuously monitored upper airway resistance during both parts of the sleep study.  They normalized all of the results by sleep phase and position.

When mouth breathing, upper airway resistance was significantly greater than during nose breathing.  Remarkably, obstructive sleep apnea (OSA) also was significantly increased during mouth breathing, even though none of the participants suffered from central OSA.  In fact, when two of the subjects were forced to breathe through their mouth, their OSA became so severe that their data could not be included in the study because there was not enough stable sleep.  That’s crazy!

Interestingly, after the study was over, they allowed the patients to return to sleep and breathe naturally.  Recordings showed that almost all of them went back to breathing exclusively through their nose.

Taken together, all of these results indicate that the nose is the preferred breathing route during sleep as it decreases airway resistance and significantly reduces episodes of sleep apnea. Many of us probably already breathe exclusively through our nose at night. However, many of us might not (including me!). Luckily, this is an easy fix. We can simply tape our mouth shut at night and reap the amazing benefits of better airflow and less apnea, which leads to deeper and more restorative sleep.

Abstract from Paper

Healthy subjects with normal nasal resistance breathe almost exclusively through the nose during sleep. This study tested the hypothesis that a mechanical advantage might explain this preponderance of nasal over oral breathing during sleep.

A randomised, single-blind, crossover design was used to compare upper airway resistance during sleep in the nasal and oral breathing conditions in 12 (seven male) healthy subjects with normal nasal resistance, aged 30+-4 (mean+-SEM) yrs, and with a body mass index of 23+-1 kg m2.

During wakefulness, upper airway resistance was similar between the oral and nasal breathing routes. However, during sleep (supine, stage two) upper airway resistance was much higher while breathing orally (median 12.4 cmH2O L-1 s-1, range 4.5–40.2) than nasally (5.2 cmH2O L-1 s-1, 1.7–10.8). In addition, obstructive (but not central) apneas and hypopnoeas were profoundly more frequent when breathing orally (apnoeahypopnoea index 43+-6) than nasally (1.5+-0.5).

Upper airway resistance during sleep and the propensity to obstructive sleep apnoea are significantly lower while breathing nasally rather than orally. This mechanical advantage may explain the preponderance of nasal breathing during sleep in normal subjects.

Journal Reference:

M.F. Fitzpatrick, H. McLean, A.M. Urton, A. Tan, D. O’Donnell, and H.S. Driver, (2003) Effect of nasal or oral breathing route on upper airway resistance during sleep, European Respiratory Journal, 22, 827 – 832, DOI: 10.1183/09031936.03.00047903.