Why Does My CPAP Mask Leak at Night?

Why Does My CPAP Mask Leak at Night?

CPAP Troubleshooting · UK

Why Does My CPAP Mask Leak at Night? 7 Common Causes & Easy Fixes

Hissing sounds, air in your eyes, a dry mouth by morning — most CPAP mask leaks come down to one of seven fixable causes.

Updated August 2026 8 min read CPAP Troubleshooting · UK Guide

In This Guide

Jump to a section.

17 Common Causes 2How to Tell If It's Leaking 3Quick Leak Checklist 4Frequently Asked Questions 5The Bottom Line

A CPAP mask leak can turn a good night's sleep into a frustrating one. You may notice air blowing toward your eyes, hear a hissing sound, wake up with a dry mouth, or find that your CPAP therapy doesn't feel as effective as it should.

The good news is that most CPAP mask leaks have a simple cause — and they can often be fixed without replacing your entire setup.

The Main Guide

7 common causes of CPAP mask leaks.

Tap each one for what to do about it.

1 Wrong CPAP Mask Size Causing Leaks +

One of the most common reasons for CPAP leaks is an incorrect mask size. A mask that is too large may not create a proper seal around your face, while a mask that is too small can create pressure points and allow air to escape.

What to do: Check your mask manufacturer's sizing guide and make sure your mask matches your facial dimensions.
2 CPAP Mask Too Tight? Why Over-Tightening Causes Leaks +

It may seem logical to tighten your mask as much as possible to stop leaks, but this can actually make the problem worse. Over-tightening can distort the cushion and create small gaps where air escapes.

Try this: Loosen the straps slightly and allow the cushion to sit naturally against your face.
3 Sleeping Position Shifting Your CPAP Mask +

Moving around during sleep can shift your mask and break the seal. Side sleepers may experience this more frequently, especially if the pillow pushes against the mask.

What to do: A CPAP-friendly pillow with space around the mask area can help reduce unwanted movement.
4 Worn-Out CPAP Cushion: When to Replace It +

CPAP mask cushions don't last forever. Over time, the material can become softer, stretched, cracked, or less effective at creating a seal. If you've started experiencing leaks after months of comfortable use, inspect the cushion for signs of wear.

What to do: A worn cushion may simply need to be replaced.
5 Facial Oils and Skincare Breaking the Mask Seal +

Natural oils, moisturisers, and skincare products can build up on the mask cushion and affect how well it seals against your skin.

What to do: Before bedtime, gently wash and dry your face and clean your mask cushion according to the manufacturer's instructions. This can help maintain a more consistent seal.
6 CPAP Mouth Leak: When Your Mouth Opens During Sleep +

If you use a nasal or nasal-pillow mask but breathe through your mouth while sleeping, you may experience what is known as a mouth leak. Signs can include:

  • Dry mouth when you wake up
  • Dry throat
  • Air escaping from your mouth
  • Reduced comfort during CPAP therapy
What to do: Depending on your situation, options such as a chin strap or a full-face mask may be worth discussing with your sleep professional.
7 CPAP Pressure Settings Causing Persistent Leaks +

Sometimes persistent leaks can be associated with pressure settings or changes in your therapy needs.

What to do: If you've checked the mask fit, cleaned the equipment, and replaced worn components but leaks continue, speak with your healthcare professional or CPAP provider before changing your pressure settings yourself.
How Can You Tell If Your Mask Is Leaking?

The common signs to watch for.

Many modern CPAP machines also provide information about mask leaks through their display or companion app.

Hearing a continuous hissing sound Air blowing toward your eyes Waking with a dry mouth Skin irritation around the mask Frequent waking during the night Feeling that therapy isn't as comfortable as before
Quick CPAP Mask Leak Checklist

Try these before replacing your mask.

✓Check the mask size
✓Refit the cushion while lying in your normal sleeping position
✓Avoid over-tightening the straps
✓Clean the cushion regularly
✓Check for cracks or worn materials
✓Consider whether your sleeping position is affecting the seal
✓Speak with your CPAP provider if leaks continue
Frequently Asked Questions

Quick answers to related searches.

Why does my CPAP mask leak if it's the wrong size?+
A mask that is too large may not create a proper seal around your face, while a mask that is too small can create pressure points and allow air to escape. Check your mask manufacturer's sizing guide and make sure your mask matches your facial dimensions.
Can a CPAP mask that's too tight cause leaks?+
Yes. Over-tightening can distort the cushion and create small gaps where air escapes. Loosen the straps slightly and allow the cushion to sit naturally against your face.
Can my sleeping position cause CPAP mask leaks?+
Yes. Moving around during sleep can shift your mask and break the seal, and side sleepers may experience this more frequently, especially if the pillow pushes against the mask. A CPAP-friendly pillow with space around the mask area can help.
How do I know if my CPAP cushion needs replacing?+
CPAP mask cushions don't last forever. Over time the material can become softer, stretched, cracked, or less effective at creating a seal. If you've started experiencing leaks after months of comfortable use, inspect the cushion for signs of wear and replace it if needed.
Can facial oils or skincare cause a CPAP mask to leak?+
Yes. Natural oils, moisturisers, and skincare products can build up on the mask cushion and affect how well it seals against your skin. Wash and dry your face before bed and clean your mask cushion according to the manufacturer's instructions.
What is a CPAP mouth leak and how do I stop it?+
A mouth leak happens when you use a nasal or nasal-pillow mask but breathe through your mouth during sleep, often causing a dry mouth or throat on waking. A chin strap or a full-face mask may help — discuss options with your sleep professional.
Could my CPAP pressure setting be causing leaks?+
Persistent leaks can sometimes be associated with pressure settings or changes in your therapy needs. If you've checked the mask fit, cleaned the equipment, and replaced worn components but leaks continue, speak with your healthcare professional before changing your pressure settings yourself.
How can I tell if my CPAP mask is leaking?+
Common signs include a continuous hissing sound, air blowing toward your eyes, waking with a dry mouth, skin irritation around the mask, frequent waking during the night, and therapy feeling less comfortable than before. Many modern CPAP machines also show leak information in their display or companion app.
Do I need a new CPAP mask if it keeps leaking?+
Not necessarily. A leaking CPAP mask doesn't always mean you need a completely new setup — the problem could be as simple as an incorrect fit, worn cushion, sleeping position, or cleaning routine. If leaks continue despite trying these adjustments, contact your healthcare professional or CPAP provider.
Related Reading

More CPAP guides on this site.

CPAP Problems & How to Fix Them Why Your CPAP Therapy Isn't Working ResMed AirTouch F20 mask guide Shop replacement cushions

The Bottom Line: A leaking CPAP mask doesn't necessarily mean you need a completely new setup. The problem could be as simple as an incorrect fit, worn cushion, sleeping position, or cleaning routine.

Taking a few minutes to identify the cause can make your CPAP therapy more comfortable and help you get the restful sleep you're looking for. If leaks continue despite trying these adjustments, contact your healthcare professional or CPAP provider for personalised advice.

This guide is for general educational purposes only and is not a substitute for personalised medical advice. Pressure settings should only ever be adjusted by, or in consultation with, your prescribing clinician or sleep specialist.

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