Why Your CPAP Therapy Isn't Working

Why Your CPAP Therapy Isn't Working

 

CPAP Troubleshooting Guide · UK 2026

Why Your CPAP Therapy Isn't Working: 12 Common Problems, Expert Solutions & Tips for Better Sleep

In most cases, it isn't the machine — it's one of a handful of fixable issues. Here's how to find yours and fix it tonight.

Updated July 2026 15 min read CPAP Troubleshooting · UK Guide


Why This Guide Matters

Why some people think CPAP isn't working.

Many people begin CPAP therapy expecting to wake up feeling refreshed after the very first night. While some experience immediate improvements, many others find themselves asking:

"Why am I still tired?"
"Why do I still snore?"
"Why is my mask leaking?"
"Why does CPAP feel uncomfortable?"
"Is my machine actually working?"

The good news is that in most cases, the problem isn't the CPAP machine itself. Instead, it's usually one or more factors affecting how effectively your therapy is being delivered.

This comprehensive guide explains the most common reasons CPAP therapy may not seem to be working, how to identify the issue, and practical steps to improve your sleep quality.

Understanding How CPAP Therapy Works

What CPAP is actually designed to do.

Before troubleshooting problems, it helps to understand the goal of therapy in the first place.

Continuous Positive Airway Pressure (CPAP) delivers a constant stream of air through a mask, preventing your airway from collapsing during sleep. This helps reduce or eliminate breathing interruptions caused by obstructive sleep apnoea (OSA).

When therapy is working effectively, it can:

  • Reduce snoring
  • Lower your Apnoea-Hypopnoea Index (AHI)
  • Improve oxygen levels
  • Reduce daytime fatigue
  • Enhance concentration
  • Support cardiovascular health
  • Improve overall sleep quality

However, these benefits depend on consistent use, proper mask fit, correct pressure settings, and regular equipment maintenance — which is exactly what this guide walks through.

Signs Your Therapy Is Working

What progress actually looks like.

Improvement is often gradual rather than overnight — these are the signals worth watching for.

🔇
Reduced or no snoring
Often the first change a partner notices.
📉
Lower AHI in your app
myAir or OSCAR showing a consistently low Apnoea-Hypopnoea Index.
More daytime energy
Less reliance on caffeine or naps to get through the day.
🌙
Fewer night wakings
Sleeping through with fewer noticeable interruptions.
🧠
No morning headache
Reduced overnight oxygen dips often mean clearer mornings.
💬
Positive partner feedback
A bed partner reporting calmer, quieter breathing overnight.
The Main Guide

12 common reasons CPAP isn't helping.

Tap each one to see the symptoms, why it matters, and how to fix it.

1 Your Mask Is Leaking +
Symptoms
  • Hissing sounds
  • Air blowing into your eyes
  • Dry eyes
  • High leak rate in myAir
  • Dry mouth
Why It Matters

A leaking mask reduces the pressure needed to keep your airway open, making therapy less effective even if your machine is running correctly.

How to Fix It
  • Adjust your headgear
  • Replace worn cushions
  • Clean the cushion daily
  • Try a different mask size
  • Consider another mask style
Expert Tip: A mask that's too tight often leaks more than one that's fitted correctly. Overtightening can distort the cushion and reduce its seal.
2 Your Pressure Is Too High +
Symptoms
  • Difficulty exhaling against the airflow
  • Aerophagia (swallowing air, bloating)
  • Mask being pushed off the face overnight
  • Waking feeling anxious or unable to settle
Why It Matters

Pressure that's set higher than you need can make exhaling uncomfortable, encourage mouth breathing and leaks, and make the mask harder to tolerate — which often leads to reduced nightly usage.

How to Fix It
  • Check if your machine has ramp or EPR/A-Flex comfort settings enabled
  • Review pressure data with your clinic
  • Ask about a pressure re-titration if symptoms persist
Expert Tip: Never adjust prescribed pressure settings yourself — always go through your sleep clinic or prescribing clinician.
3 Your Pressure Is Too Low +
Symptoms
  • Continued snoring despite regular use
  • Persistent apnoeas visible in your app's AHI data
  • Ongoing daytime fatigue
Why It Matters

If pressure isn't high enough to fully splint the airway open, breathing interruptions can continue even while the machine is running every night.

How to Fix It
  • Review your AHI trend over several weeks, not just one night
  • Share the data with your sleep clinic
  • Ask whether a titration study or auto-adjusting (APAP) mode is appropriate
Expert Tip: A single bad night can be caused by alcohol, congestion, or sleep position — look at the weekly trend before assuming your pressure needs changing.
4 You're Not Using CPAP Enough Each Night +
Symptoms
  • Daytime fatigue despite "using" CPAP
  • Low average usage hours shown in your app
  • Removing the mask partway through the night
Why It Matters

CPAP only treats sleep apnoea while it's being worn. Partial-night use means the untreated hours can still bring breathing interruptions and fragmented sleep.

How to Fix It
  • Wear CPAP every night, for the entire sleep period
  • Address comfort issues (mask fit, pressure, dryness) that cause removal
  • Track your usage hours weekly to spot patterns
Expert Tip: Most guidelines look for at least 4 hours a night, on most nights — but full-night use gives the most benefit.
5 Your Mask Doesn't Fit Properly +
Symptoms
  • Red marks or pressure sores
  • Mask shifting during the night
  • Discomfort that makes you dread putting it on
Why It Matters

An ill-fitting mask is one of the most common reasons people stop using CPAP altogether — comfort problems compound leak and pressure problems.

How to Fix It
  • Get professionally sized rather than guessing
  • Try a different mask type (nasal, nasal cradle, or full face) to match your breathing style
  • Replace worn headgear straps that have lost elasticity
Expert Tip: The "best" CPAP mask is the one that fits your face shape and breathing pattern — not necessarily the newest or most expensive model.
6 You're Experiencing Dry Mouth or Nasal Congestion +
Symptoms
  • Waking with a parched, sore throat
  • Blocked or runny nose overnight
  • Mouth breathing despite a nasal mask
Why It Matters

Dryness and congestion are common reasons people cut therapy short or avoid wearing the mask at all, even when the pressure settings themselves are correct.

How to Fix It
  • Use a heated humidifier if your machine supports one
  • Try a chin strap if you breathe through your mouth
  • Switch to a full face mask if nasal breathing is difficult
Expert Tip: Persistent congestion unrelated to CPAP (such as allergies) is worth mentioning to your GP, since it can undermine even a well-fitted mask.
7 Your Equipment Is Worn or Overdue for Replacement +
Symptoms
  • Cushion feels stiff, discoloured, or has lost its shape
  • Headgear straps have gone slack
  • Increasing leak rate over recent weeks
Why It Matters

Silicone and foam cushions naturally break down with regular washing and nightly compression, gradually losing their ability to seal properly.

How to Fix It
  • Replace cushions on the manufacturer's recommended schedule
  • Check tubing and filters for wear too, not just the mask
  • Keep a simple replacement calendar or reminder
Expert Tip: If your leak rate has crept up gradually over several weeks with no change in fit, worn-out equipment is often the cause.
8 You Have Aerophagia (Swallowing Air) +
Symptoms
  • Bloating or stomach discomfort in the morning
  • Burping frequently after waking
  • Feeling too uncomfortable to fall back asleep
Why It Matters

Swallowing air can make therapy genuinely unpleasant, which often leads to people cutting nights short or avoiding CPAP altogether.

How to Fix It
  • Try sleeping with your head slightly elevated
  • Review pressure settings with your clinic — it's often linked to pressure that's higher than needed
  • Ask about ramp settings to ease into full pressure gradually
Expert Tip: Aerophagia often improves once pressure or mask fit issues are resolved — it's rarely a standalone problem.
9 You're Not Acclimatised Yet +
Symptoms
  • Feeling claustrophobic or anxious wearing the mask
  • Difficulty falling asleep with it on
  • Frustration in the first few weeks of therapy
Why It Matters

Adjusting to sleeping with a mask and constant airflow is a genuine adjustment period for most new users — expecting instant comfort can lead to giving up too early.

How to Fix It
  • Practise wearing the mask while awake, during the day
  • Use the ramp feature to start at a lower, gentler pressure
  • Give yourself several weeks before judging whether a mask style works for you
Expert Tip: Most new users need 2–4 weeks of consistent use before therapy starts to feel natural.
10 You Have an Untreated Co-Existing Sleep Issue +
Symptoms
  • Ongoing daytime sleepiness despite a good AHI and high usage hours
  • Difficulty falling or staying asleep unrelated to breathing
  • Restless legs or frequent unexplained waking
Why It Matters

CPAP treats obstructive sleep apnoea specifically — it won't resolve unrelated conditions like insomnia or restless legs syndrome, which can exist alongside OSA.

How to Fix It
  • Discuss ongoing symptoms with your GP or sleep clinic even if your CPAP data looks good
  • Keep a simple sleep diary to identify patterns
Expert Tip: Good CPAP data (low AHI, high usage) but persistent tiredness is a genuine reason to ask your clinic about further assessment, not a reason to assume the machine has failed.
11 Your Sleep Position Is Affecting Therapy +
Symptoms
  • Higher AHI or more leaks on nights you sleep on your back
  • Mask pulled off-centre after switching sides
  • Hose tangling or pulling during movement
Why It Matters

Some people have more airway collapse when sleeping on their back, and hose position or mask style can make side sleeping harder to maintain.

How to Fix It
  • Consider a mask with a top-of-head tube connection for easier side sleeping
  • Try a positional aid if back-sleeping worsens your AHI
  • Review night-by-night data to see if position correlates with events
Expert Tip: Masks like the ResMed AirFit N30i or AirFit F30i route the hose over the top of the head specifically to reduce this problem for side sleepers.
12 Your Diagnosis or Titration May Need Reviewing +
Symptoms
  • Persistent symptoms despite resolving fit, leak, and usage issues
  • Significant weight change since your original sleep study
  • Ongoing high AHI that doesn't respond to adjustments
Why It Matters

Pressure needs can change over time, and in rarer cases the original diagnosis or settings may need reassessing entirely.

How to Fix It
  • Request a review appointment if problems persist after working through the other reasons in this guide
  • Bring your usage and AHI data to the appointment
Expert Tip: This should be one of the last things you consider, after ruling out mask fit, pressure comfort settings, and consistency of use — not the first assumption.
CPAP Troubleshooting Checklist

The quick-reference version.

A fast way to match your symptom to a likely cause and next step.

Problem Symptoms Solution
Air Leaks Dry eyes, noise Replace cushion
Wrong Mask Discomfort Try another style
Low Usage Daytime fatigue Wear CPAP every night
Pressure Issues Persistent apnoeas Review settings
Dry Mouth Waking thirsty Heated humidifier
How Long Does CPAP Take to Work?

Progress that builds over time.

CPAP works best as a long-term, consistent treatment — not an overnight fix.

1
Week 1
  • Getting used to the mask
  • Minor improvements in alertness
2
Weeks 2–4
  • Less snoring
  • Better concentration
  • More energy
3
Months 1–3
  • Improved mood
  • Better blood pressure
  • Reduced daytime sleepiness
4
After 6 Months
  • Maximum long-term health benefits
  • Better therapy compliance
  • Lower cardiovascular risk
When to Replace Your CPAP Equipment

Worn parts undo good therapy quietly.

A rough replacement schedule to keep your seal — and your results — consistent.

Mask cushion — every 1–3 months (silicone) or ~monthly (memory foam)
Headgear — every 6 months, or sooner if straps feel loose
Tubing — every 3–6 months
Disposable filters — monthly
Reusable filters — every 2 weeks, rinsed and air-dried
Humidifier water chamber — every 6 months
Choosing the Right CPAP Mask

The right mask solves more problems than any setting change.

Match the mask to how you actually breathe and sleep, not just what looks newest.

👃
Nasal breathers
A nasal or nasal cradle mask, such as the AirFit N20 or AirFit N30i, is usually lighter and less intrusive.
👄
Mouth breathers
A full face mask, such as the AirTouch F20 or AirFit F30i, covers nose and mouth for a consistent seal.
🛌
Side sleepers
Look for a top-of-head tube connection to keep the hose out of the way as you move.
🧴
Sensitive skin
Memory foam cushions, such as AirTouch, are gentler against the face than standard silicone.
💷
Budget-conscious
Alternatives like the BMC F5A offer dependable full face coverage at a lower cost.
📐
Dislike bulky masks
Compact minimal-contact designs, such as the AirFit F40, reduce facial coverage while keeping a full face seal.
How to Improve Therapy Results

Small habits, compounded nightly.

Wear your CPAP every night, for the entire sleep period
Check your mask seal and leak rate regularly
Clean your equipment on a consistent schedule
Replace worn cushions and headgear promptly
Use a humidifier if dryness is an issue
Attend follow-up appointments with your sleep clinic
When to Contact Your Sleep Clinic
🩺 Speak to your clinic if you notice:
• Persistent high AHI despite fit and pressure fixes
• Ongoing daytime sleepiness despite good usage data
• Skin breakdown or sores that don't improve
• Chest pain, palpitations, or breathlessness
• Significant weight change since your last review
• Symptoms that don't match what this guide describes
Frequently Asked Questions

Quick answers to common questions.

Why do I still snore while using CPAP?+
Continued snoring on CPAP usually points to a leaking mask, pressure that's set too low for your needs, or a mask that has shifted out of position overnight. Check your leak rate in the myAir or OSCAR app, confirm your cushion size, and speak to your clinic if snoring persists after adjusting the fit.
Can I skip CPAP for one night?+
Skipping a single night won't undo long-term progress, but sleep apnoea symptoms typically return the same night therapy is missed, since CPAP treats the condition only while it's being used. Consistent nightly use is what delivers the cardiovascular and daytime-alertness benefits.
Why do I wake up with a dry mouth?+
Dry mouth is commonly caused by mouth breathing during sleep, air leaking around the mask, or insufficient humidification. A heated humidifier, a chin strap for mouth breathers, or switching to a full face mask can all help.
Should I replace my CPAP cushion every month?+
Replacement schedules vary by cushion material. Silicone cushions typically last 1–3 months, while memory foam cushions such as AirTouch usually need replacing roughly every month. Follow the manufacturer's guidance and replace sooner if the seal feels less effective.
How do I know if my pressure is correct?+
Your CPAP app (such as myAir) or a program like OSCAR can show your AHI, leak rate, and pressure trends. Persistently high AHI, frequent leaks, or ongoing daytime fatigue despite regular use are signs to discuss your pressure settings with your sleep clinic.
Can I use CPAP if I have a cold?+
Yes, most people can continue CPAP therapy with a cold, though nasal congestion may make it feel less comfortable. A heated humidifier can ease dryness and congestion, and a full face mask may help if nasal breathing is difficult. Speak to your clinician if breathing feels significantly restricted.
Which ResMed mask is best for side sleepers?+
Masks with a top-of-head tube connection, such as the ResMed AirFit N30i, AirTouch N30i, or AirFit F30i, tend to work best for side sleepers because the hose stays out of the way and reduces mask displacement during movement.

If your CPAP therapy doesn't feel like it's working, the machine is rarely the problem. Air leaks, pressure comfort, mask fit, and consistent nightly use account for the vast majority of cases — and each one has a straightforward fix.

Work through the reasons in this guide in order, track your progress in your CPAP app, and don't hesitate to bring your data to your sleep clinic if problems persist. Therapy that feels wrong today is very often one adjustment away from working well.

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 clinic.

If you experience chest pain, palpitations, severe breathlessness, or any symptom that concerns you, seek medical advice promptly rather than relying on this guide alone.

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