Short answer: waking with a dry mouth, a sore throat, bad breath or a pillow that is damp can be clues that you breathe through your mouth at night. It has several possible causes, from a blocked nose to the way you breathe in sleep, and it is worth sorting out. This is a self-check, not a diagnosis.
Why it matters what you breathe through
The nose warms, filters and moisturises the air you breathe. Breathing through the mouth for long stretches, particularly asleep, dries the mouth. Less saliva can mean more bad breath, a higher chance of cavities and irritated gums. It can also go along with snoring and poor-quality sleep.
Mouth breathing is a sign, not a diagnosis. The question is why it is happening.
A simple self-check
Over several mornings, notice whether any of these apply to you:
- A very dry mouth or throat when you wake, or a sore throat that fades during the day.
- Bad breath on waking that is stronger than usual.
- A damp patch on the pillow or waking with your mouth open.
- Snoring, or a partner noticing your mouth is open or you pause in your breathing.
- Feeling unrefreshed despite enough hours in bed, or headaches on waking.
- Trouble breathing through your nose during the day.
One of these once in a while is not a worry. Several, on most mornings, are worth mentioning to a professional.
Try this: when you are awake and relaxed, close your mouth and breathe in through your nose for a minute. If it is hard or blocked on one or both sides, tell your doctor. A blocked nose is a common reason for mouth breathing.
Possible reasons
- Nasal congestion from colds or allergies, or a structural problem such as a deviated septum. A doctor or an ear, nose and throat specialist can assess these.
- Habit. Some people simply fall into mouth breathing and keep it up.
- Sleep-disordered breathing. Snoring and sleep apnea can go along with open-mouth breathing. If you have loud snoring, pauses or heavy daytime tiredness, a sleep evaluation may be worth having. Our post on how to tell if snoring may be sleep apnea goes through the signs.
- Jaw and tongue position. How the jaw rests and how much room the tongue has can affect the airway, which is something we can look at in an exam.
What may help, and what to ask about
- Treat the obvious first. Talk to your doctor about congestion or allergies.
- Keep the bedroom comfortable. Dry air can make dry mouth worse, and a glass of water nearby can help.
- Ask for an airway and bite exam. We can look at the throat, tongue, jaw and bite, and talk about whether a sleep test or another specialist makes sense.
- Do not tape your mouth shut or try gadgets on your own. If you have a blocked nose or possible sleep apnea, that can be unsafe.
A perspective on breathing
Yoga traditions place a lot of emphasis on slow, calm breathing through the nose, and many people find a few quiet minutes of it relaxing. It is a perspective from a long tradition, not a proven treatment for sleep problems, and it does not replace an exam if you snore, pause or feel tired.
If you read our post on clocks falling back and your mouth, this goes a step further: not just why a few nights of poor sleep show up in your mouth, but how to tell if night-time mouth breathing is a longer pattern.
Waking up dry-mouthed or unrefreshed?
A short airway and bite exam can help sort out what may be going on and whether a sleep test or another specialist makes sense.
Frequently Asked Questions
How do I know if I breathe through my mouth at night?
Clues include waking with a very dry mouth or sore throat, strong bad breath, a damp pillow, snoring, or a partner noticing your mouth is open. None of these proves it on its own. If several apply on most mornings, mention it to us or your doctor.
Is mouth breathing the same as sleep apnea?
No. Mouth breathing is a pattern. Sleep apnea is a medical condition in which breathing repeatedly pauses during sleep, and it is diagnosed with a sleep evaluation. Mouth breathing can go along with sleep apnea, so persistent snoring, pauses or heavy daytime tiredness are worth following up.
What causes mouth breathing?
Common causes include nasal congestion, allergies, a deviated septum, habit, and sleep-disordered breathing. The jaw and tongue position can also play a part. Finding the cause is the key step, and it may involve your doctor or a specialist.
Can mouth breathing affect my teeth?
It can dry the mouth, and less saliva may raise the risk of cavities, gum irritation and bad breath. Good cleaning habits, plenty of water and regular check-ups help. We can also look for signs of dry-mouth wear at your visit.
Should I tape my mouth shut at night?
We do not recommend trying this on your own. If your nose is blocked or you may have sleep apnea, covering the mouth can be unsafe. Please talk to your doctor or to us first so the cause can be looked at.
This article is for general educational purposes and is not a substitute for professional dental or medical advice or diagnosis. If you snore loudly, pause in your breathing or feel very tired in the day, please call our office and speak with your doctor.
Related: Sleep Apnea · TMJ & Sleep Center · How to Tell If Snoring May Be Sleep Apnea · Book a Consultation