The Science of a Closed Mouth
The Science of a Closed Mouth
Most of us breathe through the nose by day without a second thought. At night, it can change. As the body relaxes into sleep, the mouth may drift open and the breath begins to move through the mouth instead. Most of us never notice it happening. We only notice how we wake.
What happens inside the mouth
Saliva is the mouth's own care. It helps neutralize acids, protects the surface of the teeth and keeps the mouth comfortable. Its flow naturally slows while we sleep, which makes the night a quieter, drier time for the mouth.
When the mouth stays open, that dryness deepens. In a University of Otago study, researchers monitored the mouths of healthy adults through the night. During sleep with mouth breathing, the mouth became more acidic than during sleep with nasal breathing, at times falling below the level at which tooth enamel begins to soften.
Other studies have associated habitual mouth breathing with more gum inflammation and with higher levels of bacteria linked to cavities. These were small observational studies. They show a connection, not a cause, but they help explain why dentists pay attention to how we breathe.
What the nose quietly does
The nose warms, filters and humidifies each breath before it reaches the lungs.
It also carries something quieter. The sinuses produce nitric oxide, a molecule that travels to the lungs mainly when we breathe through the nose. In one small study of healthy adults, oxygen levels measured through the skin were higher during nasal breathing than during mouth breathing.
Through the nose
- Each breath is warmed, filtered and humidified
- Carries nitric oxide from the sinuses to the lungs
- Leaves the mouth at rest through the night
Through the mouth
- The breath reaches the lungs drier and unfiltered
- The mouth becomes drier through the night
- Linked in research to a more acidic mouth during sleep
Summarized from the studies listed below.
Where a sleep strip fits
A sleep strip, sometimes called mouth tape, rests over closed lips through the night, gently encouraging the breath to stay with the nose. The Silentias Hydrating Sleep Strip does one simple thing: it keeps your lips softly closed until morning.
Shop the StripA note on the research. Research on sleep strips themselves is still young, and we share these studies to explain the difference between nasal and mouth breathing, not as promises about any product. Silentias is designed for adults. If breathing through your nose is difficult, or if you have a sleep or breathing condition, please speak with your doctor before use.
References
- Choi JE, Waddell JN, Lyons KM, Kieser JA. Intraoral pH and temperature during sleep with and without mouth breathing. Journal of Oral Rehabilitation. 2016;43(5):356–363.
- Humphrey SP, Williamson RT. A review of saliva: normal composition, flow, and function. Journal of Prosthetic Dentistry. 2001;85(2):162–169.
- Sharma RK, Bhatia A, Tewari S, Narula SC. Distribution of gingival inflammation in mouth breathing patients: an observational pilot study. Journal of Dentistry Indonesia. 2016;23(2):28–32.
- Mummolo S, Nota A, Caruso S, et al. Salivary markers and microbial flora in mouth breathing late adolescents. BioMed Research International. 2018;2018:8687608.
- Lundberg JO, Farkas-Szallasi T, Weitzberg E, et al. High nitric oxide production in human paranasal sinuses. Nature Medicine. 1995;1(4):370–373.
- Lundberg JO, Settergren G, Gelinder S, et al. Inhalation of nasally derived nitric oxide modulates pulmonary function in humans. Acta Physiologica Scandinavica. 1996;158(4):343–347.
This page is for educational purposes and is not medical advice.