Mouth taping and nasal breathing glossary: 30 terms explained

This glossary defines 30 terms you'll come across when reading about mouth taping, nasal strips and breathing during sleep. It covers sleep study measures such as the AHI, devices such as nasal strips, chin straps and CPAP, and the parts of the nose they act on. Each entry gives a short, sourced definition, in alphabetical order.

Terms from A to D

Apnea-hypopnea index (AHI)

The number of apneas, complete pauses in breathing, and hypopneas, partial blockages of airflow, per hour of sleep. Sleep Foundation says under 5 is normal, 5 to 14 is mild sleep apnea, 15 to 29 moderate and 30 or more severe.

Buteyko method

A breathing approach that encourages nose breathing, using mouth taping at night. A 2009 randomized trial tested Buteyko-style taping in 51 adults with asthma and found no effect on asthma control.

Chin strap

A strap that holds the jaw closed during sleep. The NHS lists it as an option when the mouth falls open while you sleep. A 2014 study in 26 adults with sleep apnea found a chin strap alone didn't improve snoring.

CPAP

Short for continuous positive airway pressure. The American Academy of Sleep Medicine calls it the leading treatment for sleep apnea, and says it keeps the airway open by gently providing air through a mask worn during sleep.

Decongestant nasal spray

A spray that reduces swelling inside the nose. The NHS says decongestant sprays and drops shouldn't be used for more than 5 days at a time, because longer use can make stuffiness worse.

Deviated septum

When the cartilage and bone dividing the nose in the middle aren't straight. Healthdirect says most people have a mild one that causes no problems, while a severe one can make breathing harder, usually on one side. See deviated septum symptoms.

Terms from E to M

Epworth Sleepiness Scale

A short questionnaire about daytime sleepiness that asks how likely you are to fall asleep in eight everyday situations. Sleep Foundation says doctors use it to help identify excessive daytime sleepiness.

Home sleep apnea test

A test you wear at home to collect information about your breathing during sleep. The American Academy of Sleep Medicine says the devices measure breathing and blood oxygen, and that a negative result isn't always enough to rule out sleep apnea.

Hypoallergenic

A label suggesting a product is less likely to cause allergic reactions. FDA says there are no federal standards or definitions for the term on cosmetics, and that it means whatever a particular company wants it to mean.

Internal nasal dilator

A plastic or metal device placed inside the nostrils. US regulations say it works by pushing the nostrils open or by gently pressing on the strip of tissue between them.

Mandibular advancement device

A mouthpiece that holds the lower jaw forward to bring the tongue forward, according to the NHS. A 2015 guideline recommends oral appliances, rather than no therapy, for adults who want treatment for snoring without sleep apnea.

Mouth breathing

Breathing through your mouth instead of your nose most of the time. Cleveland Clinic says it often happens when air can't get in through the nose, and that it isn't a serious health issue for adults, though it can affect children's growth.

Mouth leak

Air escaping through the mouth during CPAP. SleepApnea.org says mouth breathing on CPAP can lead to dry mouth, sore throat, air leaks and less effective therapy. Our article on mouth tape and CPAP covers the options.

Mouth taping

Placing tape over the lips before bed to encourage nose breathing during sleep, according to Sleep Foundation. A small 2022 study of mouth breathers with mild sleep apnea found snoring roughly halved after a week of taping (the research). Sleep Foundation says people with untreated sleep apnea, chronic nasal congestion or trouble breathing through the nose shouldn't use it.

Terms from N to O

Nasal cycle

A normal pattern in which one side of the nose becomes more congested while the other opens up. Cleveland Clinic says the sides switch every four to six hours. Read more in the nasal cycle.

Nasal strip

An external nasal dilator. US regulations describe it as layers of material with a spring and a skin adhesive that pulls the nostrils open, decreasing airway resistance and increasing nasal airflow. In a 2000 placebo-controlled trial, strips lowered snoring frequency in people with chronic rhinitis.

Nasal valve

The passageway inside the nose, which a 2019 study describes as having the smallest cross-sectional area of the upper airway. Cleveland Clinic describes an internal valve in the middle of the nose and an external valve near the nostrils. A 1997 study found a nasal strip increased nasal valve area in athletes at rest.

Nasal valve collapse

When the nasal valve narrows and stops air flowing freely through the nose. Cleveland Clinic calls it one of the most common causes of nasal obstruction. See nasal valve collapse.

Nitric oxide

A gas found in air from the nasal airways. A 1995 study in Nature Medicine found it's produced by cells lining the sinuses and is present in sinus air in very high concentrations. Our explainer on nitric oxide and nasal breathing covers what's known.

Obstructive sleep apnea

A common and serious sleep disorder in which the airway becomes blocked again and again during sleep, according to the American Academy of Sleep Medicine. Snoring with silent pauses and choking or gasping is a warning sign. Mouth tape and nasal strips aren't treatments for it.

Orthosomnia

A term coined by sleep researchers for people who seek treatment for sleep problems they've self-diagnosed from sleep tracker data, sometimes chasing perfect sleep numbers.

Oxygen desaturation index

How many times per hour, on average, blood oxygen falls below normal for 10 seconds or longer, according to Sleep Foundation. Doctors may review it alongside the AHI.

Terms from P to V

PFAS

A group of widely used, long-lasting chemicals that break down very slowly. The EPA says many are found in the blood of people and animals around the world.

Polysomnography

The full overnight sleep study. The American Academy of Sleep Medicine says it records brain waves, heart rate and breathing, along with eye and limb movements and blood oxygen.

Rebound congestion

Nasal congestion caused by overusing decongestant sprays, also called rhinitis medicamentosa. Cleveland Clinic says it's reversible, and most people improve after they stop overusing the sprays. See decongestant spray rebound.

Saline rinse

Rinsing the nasal passages with salt water. FDA says to use only distilled, sterile or previously boiled water, because tap water isn't adequately filtered or treated for use in the nose. Our guide on how to use a saline rinse covers the steps.

Snoring index

The number of snores per hour, measured in a sleep study. A 1998 nasal strip study counted it per hour of time in bed, and the 2015 and 2022 mouth tape studies both reported it.

Turbinates

Small structures inside the nose that cleanse, heat and humidify air on its way to the lungs. Cleveland Clinic says they can swell from irritation, allergies or infection, and some people develop long-term swelling.

Upper airway resistance syndrome

A pattern of snoring and repeated breathing-effort arousals during sleep without the oxygen drops typical of sleep apnea. A 2012 review says daytime sleepiness is the main diagnostic feature. See upper airway resistance syndrome.

Vestibular shield

A device worn in the mouth to help you breathe through your nose while you sleep. The NHS lists it alongside a chin strap as an option when the mouth falls open during sleep.

More on these topics is on our nasal breathing topic page.

If you want to try mouth tape and nasal strips together, our pick is the Titan Sleep System, which pairs TitanAir Nasal Strips with Titan Mouth Tape.

Read next

• What is mouth taping?
• How nasal strips work
• Nasal vs. mouth breathing

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.