Sleeping with your mouth open: causes, risks, and how to stop

5 February 2026

Sleeping with your mouth open: causes, risks, and how to stop

If you regularly wake up with a dry mouth, bad breath, or a sore throat, there’s a good chance you’re sleeping with your mouth open- even if you don’t notice it at the time.

It’s a surprisingly common concern, which is why people search things like:

• How to stop sleeping with mouth open (390 searches/month)

• Why do I sleep with my mouth open (260)

• Is it bad to sleep with your mouth open (110)

At Knighton Dental, we see this often. And while it’s not always a serious issue, it is worth addressing if it’s happening most nights- mainly because it can impact your comfort, breath, and long-term dental health.

Why do I sleep with my mouth open?

In most cases, mouth breathing during sleep isn’t a “habit” you’ve chosen. It’s your body’s way of getting enough air. If your nose is blocked or breathing feels restricted, your mouth naturally takes over.

The most common reasons include:

• Nasal blockage (colds, allergies, sinus congestion)

• Snoring or disrupted breathing at night

• A deviated septum or narrow nasal passages

• Enlarged tonsils/adenoids (more common in children)

• Sleeping on your back (which can worsen mouth opening)

• Dry room air (especially during winter heating)

• Long-term oral posture patterns linked to chronic congestion

You might also notice this comes in phases- for example, it worsens during hay fever season or when you’re fighting a cold.

Is it bad to sleep with your mouth open?

If it only happens occasionally, for example, when you’re congested it’s usually not a major concern.

The problem is when it becomes your normal. When you breathe through your mouth overnight, your mouth dries out, and that matters because saliva is protective. It helps neutralise acids, supports the natural balance of bacteria, and protects enamel. Without enough saliva, your mouth is simply more vulnerable.

Does sleeping with mouth open cause bad breath?

It can, yes  and it’s one of the first things people notice.

When your mouth is dry overnight, bacteria can build up more easily, particularly on the tongue. That combination is a very common reason for stronger “morning breath” that doesn’t feel normal.

If you’re brushing well and still waking up with persistent bad breath and dryness, it’s a sign the cause may be breathing-related rather than purely hygiene-related.

Can sleeping with mouth open cause cavities?

Mouth breathing doesn’t directly cause cavities on its own, but it can increase risk over time.

The reason is simple: less saliva means less natural protection. Saliva helps wash food particles away and neutralise acids that weaken enamel. If your mouth is dry for hours every night, teeth can be exposed to a more acidic environment for longer- especially if you also snack late, sip sugary drinks, or already have areas that trap plaque.

What about sore throat, sore tongue, and tonsil stones?

These are all very common symptoms of sleeping with your mouth open.

Because air is moving directly over soft tissues, it can leave you waking up with:

• A dry or scratchy throat

• A sore or burning tongue

• A stronger taste or smell in the mouth

• More noticeable tonsil stones (or a “something stuck” feeling)

Even if tonsil stones aren’t caused by mouth breathing alone, dryness can make the symptoms (and breath changes) feel worse.

Does sleeping with your mouth open affect your jawline or face shape?

You’ll see a lot of bold claims online about mouth breathing and face shape- so it’s worth setting expectations clearly.

In children, long-term mouth breathing is associated in research with changes in facial growth and jaw development, mainly because the face is still developing.

In adults, those dramatic changes are unlikely because growth is complete. However, mouth breathing can still be linked with jaw tension, discomfort on waking, and poor-quality sleep which is usually what people are feeling when they ask this question.

How to stop sleeping with your mouth open (5 practical steps)

If you’re looking for a place to start, aim to solve the cause first  and protect the teeth while you’re doing it.

1) Help your nose do its job

If nasal blockage is the main trigger, improving nasal breathing often makes the biggest difference:

• Saline spray/rinse before bed

• Warm shower or steam

• If allergies are a regular issue, speak to a pharmacist/GP about suitable options

2) Adjust your sleeping position

Sleeping on your back can make snoring and mouth opening more likely. Side sleeping often helps, especially if you notice it’s worse when you’re on your back.

3) Improve your bedroom air

Dry air makes dryness worse. If heating is on overnight, a humidifier can help some people, or even a simple bowl of water near a radiator.

4) Protect your teeth if you clench or grind

If you wake up with jaw soreness, headaches, or sensitive teeth, you may be grinding at night. A dental guard can help protect enamel and reduce wear.

5) Know when it needs a medical check

If you have loud snoring, gasping/choking, morning headaches, or daytime tiredness, speak to your GP about sleep apnoea assessment. Mouth breathing and waking with a dry mouth can be more common when sleep-disordered breathing is involved.

A quick note on mouth taping

You’ve probably seen mouth taping trending. While a recent 2025 systematic review discussed it, the overall evidence is limited and it isn’t suitable for everyone especially if you have nasal obstruction. In short: it’s not a first step, and you shouldn’t try anything that could restrict breathing.

A safer approach is to improve nasal breathing first and address the underlying reason you’re mouth breathing in the first place.

FAQs

Can a dentist help with mouth breathing?

Yes. We can check for signs of dry mouth, enamel wear, gum irritation, and grinding. We can also recommend ways to protect your teeth and advise if a GP or ENT review could be useful.

Why is mouth breathing bad for teeth?

Because saliva protects teeth. When your mouth is dry overnight, acids and bacteria can have more impact, which may increase the risk of decay, irritation, and bad breath over time.

Does sleeping with your mouth open always mean sleep apnoea?

Not always. It can be caused by congestion, allergies, sleep position, or habits. But if you also snore heavily or feel tired in the day, it’s worth getting checked.

When to book with Knighton Dental

If you’re waking up with a dry mouth most mornings, getting frequent bad breath despite good oral hygiene, seeing more cavities than expected, or feeling jaw tension on waking, a check-up can help you get clarity and a plan.