CPAP Machine for Sleep Apnoea: UK Guide

CPAP machine therapy for sleep apnoea is the most widely recommended treatment for moderate to severe obstructive sleep apnoea (OSA) in the UK. By delivering a continuous stream of pressurised air through a mask, a CPAP machine keeps the upper airway open throughout the night, preventing the repeated breathing interruptions that disrupt sleep and reduce blood oxygen levels. This article explains how CPAP works, how to access it on the NHS, how to choose the right mask, what side effects to expect, and how quickly you might notice an improvement.

What is sleep apnoea and how does a CPAP machine treat it?

CPAP therapy keeps the upper airway open by delivering pressurised air through a mask, preventing the repeated collapses that cause apnoeas. NICE recommends it as first-line treatment for moderate to severe OSA based on AHI and symptom impact.

Sleep apnoea is a condition in which the upper airway repeatedly collapses during sleep, causing breathing to stop and restart, often dozens or even hundreds of times a night. The most common form is obstructive sleep apnoea (OSA), where the soft tissues at the back of the throat relax and block airflow. A less common form, central sleep apnoea, occurs when the brain fails to send the correct signals to the breathing muscles. Both types disrupt sleep architecture and reduce blood oxygen levels, leading to daytime sleepiness, poor concentration and, over time, an increased risk of cardiovascular problems.

Continuous positive airway pressure (CPAP) therapy is the first-line treatment recommended by NICE for moderate to severe OSA.^[1][2] The machine works by delivering a continuous, gently pressurised stream of air through a mask, which acts as a pneumatic splint to keep the airway open throughout the night. This prevents the collapse that causes apnoeas and hypopnoeas (partial obstructions), allowing the person to breathe normally and move through the natural stages of sleep without interruption.

NICE guidance (TA139 and NG202) supports CPAP as the primary treatment for adults with moderate to severe OSA.^[1][2] Eligibility is based on a combination of the apnoea-hypopnoea index (AHI, which counts breathing interruptions per hour) and the impact of symptoms on quality of life, not on AHI alone. A clinician will weigh both factors when recommending treatment.

Diagnosis in the UK is typically made following a sleep study, which may be a home-based oximetry or respiratory polygraphy test, or a full in-laboratory polysomnography for more complex cases. NICE NG202 sets out the diagnostic pathway in detail, including when home testing is appropriate and when a more detailed in-laboratory study is needed.^[1][3]

For people who cannot tolerate CPAP, or whose OSA is mild, NICE also recognises alternatives such as mandibular advancement devices (custom-fitted oral appliances that hold the jaw forward to keep the airway open) and positional therapy (for OSA that occurs mainly when lying on the back). A sleep clinician can advise on which option is most suitable.

How does a CPAP machine work and what does it feel like to use?

A CPAP machine pressurises filtered room air and delivers it through a mask; auto-adjusting (APAP) models vary pressure breath by breath for greater comfort. A ramp feature and heated humidifier help new users acclimatise.

A CPAP machine draws in room air, filters it, and uses a small motor to pressurise it before delivering it through a flexible tube to a mask worn over the nose, mouth, or both. The pressure is measured in centimetres of water (cmH2O) and is set by a clinician based on the results of a sleep study or an auto-titrating trial. Modern auto-adjusting CPAP (APAP) devices continuously monitor breathing and vary the pressure breath by breath, which many users find more comfortable than a fixed-pressure machine.

For most new users, the sensation of wearing a CPAP mask takes some adjustment. The airflow can initially feel forceful, and some people describe a mild claustrophobic feeling when first putting on the mask. Many machines include a ramp feature, which starts at a low pressure and gradually increases as the user falls asleep, making the experience gentler. The duration and range of the ramp varies between devices and models, so refer to your device manual or ask your sleep clinician for the settings appropriate to your machine. Heated humidifiers, which attach directly to the machine, add moisture to the air and significantly reduce dryness in the nose and throat, one of the most common early complaints.

CPAP machines are relatively compact and quiet. Noise levels vary between models and manufacturers, so check the technical specification for your particular device. Most modern machines record usage data, including hours of use per night, mask leak rates and residual AHI, which a sleep clinician can review to fine-tune settings.

Consistent nightly use is important. Clinical guidelines and research studies commonly use four or more hours of use per night as a benchmark for assessing adherence, but greater nightly use is associated with better outcomes.^[1] If you are struggling to use the machine for this long, speak to your sleep clinic rather than stopping therapy.

Can I get a CPAP machine on the NHS, or do I need to pay privately?

NHS CPAP, including the machine, mask and follow-up, is free at the point of use for eligible patients in the UK following a confirmed OSA diagnosis via a sleep clinic. Private options are available for those who do not meet the NHS threshold or prefer not to wait.

NHS CPAP therapy is available to eligible patients diagnosed with OSA through a sleep clinic. In England, Scotland and Wales, the machine, mask, tubing and ongoing clinical support are provided free of charge at the point of use.^[4] In Northern Ireland, equivalent services are provided through the Health and Social Care (HSC) system, though local arrangements may differ. Referral is usually made by a GP to a local sleep service, where a diagnostic sleep study is arranged. If OSA is confirmed and meets the threshold for treatment, the sleep team will set up CPAP and provide follow-up appointments to review progress and adjust settings. Waiting times vary considerably between NHS trusts and Integrated Care Boards (ICBs), and some areas have longer waits for initial assessment.

Patients who prefer not to wait, or who do not meet the NHS threshold but still have troublesome symptoms, may choose to access CPAP privately. Private sleep studies and CPAP set-up are available through independent sleep clinics and some online services. The cost of a private CPAP machine varies depending on the model and features, and ongoing consumables such as masks, filters and tubing represent an additional expense. It is worth noting that private CPAP machines are purchased outright, whereas NHS machines are typically loaned to the patient and remain the property of the trust.

For those exploring weight management as part of a broader approach to OSA (excess weight is a significant risk factor), Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online weight-management consultations, with prescriber review and pharmacist support. Any weight-management medicine would only be prescribed where clinically appropriate following a consultation. Regardless of the route chosen, any CPAP prescription or titration should be overseen by a qualified clinician with access to sleep study data.

Choosing the right CPAP mask and settings for your needs

The three main mask types are nasal, full-face and nasal pillow; the right choice depends on breathing pattern, facial anatomy and comfort. Pressure settings must be determined and adjusted by a clinician, not independently.

The right CPAP mask is one that seals effectively without causing pressure sores, suits your breathing pattern, and is comfortable enough to wear for a full night. There are three main mask types available in the UK:

• Nasal masks: Cover the nose only and are the most commonly prescribed type. They suit people who breathe through their nose and are generally lighter and less intrusive.

• Full-face masks: Cover both the nose and mouth, making them suitable for mouth breathers or those with nasal congestion. They tend to be bulkier but are essential for some users.

• Nasal pillow masks: Sit at the entrance to the nostrils rather than over the nose. They are minimal in design, allow glasses to be worn, and suit people who feel claustrophobic in larger masks.

Mask fit is critical. Even a small leak around the seal can reduce therapy effectiveness and cause noise that disturbs a bed partner. Factors such as facial hair or higher therapy pressures can affect fit, and it is common to try more than one style before settling on a preference. Most NHS sleep services and private providers offer mask fitting appointments, and your sleep team can support you in finding an alternative if your first mask does not suit you.

CPAP pressure settings are determined by a clinician and should not be adjusted without guidance. Auto-adjusting (APAP) machines set a pressure range rather than a fixed value, giving the device flexibility to respond to changes in sleeping position, alcohol consumption or nasal congestion. If you feel the pressure is too high or too low, or if your machine data shows a persistently elevated residual AHI, contact your sleep clinic for a review rather than altering settings independently.

What side effects and problems can a CPAP machine cause?

Common side effects include nasal dryness, mask leaks, aerophagia and dry mouth, most of which can be resolved with a humidifier, mask refitting or pressure adjustment. Serious adverse effects are uncommon; chest pain or significant breathlessness during CPAP use requires prompt medical advice.

CPAP therapy is generally well tolerated, but a range of side effects can occur, particularly in the first few weeks of use. The most frequently reported problems include:

• Nasal dryness and congestion: Caused by the airflow drying the nasal mucosa. A heated humidifier and nasal saline spray usually resolve this.

• Mask leaks and pressure sores: Often a sign of poor mask fit. A different mask size or style, or a mask liner, can help.

• Aerophagia (swallowing air): Some users experience bloating or belching. A clinician may recommend lowering the pressure slightly or switching to a bilevel device (BiPAP) if this is troublesome.

• Claustrophobia or anxiety: More common with full-face masks. Gradual acclimatisation during waking hours and switching to a nasal pillow mask can ease this.

• Dry mouth: Usually indicates mouth breathing during sleep. A chin strap or full-face mask can help retain moisture.

Serious adverse effects from CPAP are uncommon. However, if you develop chest pain, significant shortness of breath or a new or worsening headache during CPAP use, contact your GP or call NHS 111 for advice. In a life-threatening emergency, call 999.

Maintaining clean equipment is important. Masks, tubing and humidifier chambers should be washed regularly according to the manufacturer's instructions for your specific device, including guidance on frequency, suitable cleaning products and water type, to prevent bacterial or mould growth.

If you experience a suspected side effect from any medication used alongside your sleep apnoea treatment, or if you believe a medical device (including your CPAP machine) has malfunctioned and caused harm, both can be reported to the MHRA via the Yellow Card scheme at yellowcard.^[12]mhra.gov.uk.

How long will it take before I notice an improvement in my sleep?

Many people notice improved daytime sleepiness and energy within the first few weeks of consistent CPAP use. Longer-term benefits, including modest blood pressure reductions, accumulate with sustained nightly use.

Many people with OSA notice an improvement in daytime sleepiness and energy levels within the first few weeks of consistent CPAP use, though the timeline varies depending on the severity of the condition and how well the therapy is tolerated. Subjective improvements in mood, concentration and morning headaches often follow. The time taken to see meaningful changes in standardised measures such as the Epworth Sleepiness Scale varies between individuals; if you are not noticing any benefit after four to six weeks of regular use, speak to your sleep clinic.

Longer-term benefits accumulate with sustained nightly use. Evidence supports modest reductions in blood pressure and improvements in daytime sleepiness with consistent CPAP therapy.^[5][6] Claims of a reduced risk of hard cardiovascular events (such as heart attack or stroke) are less certain: randomised trial evidence on these outcomes is mixed, and any benefit appears to be linked to adherence and patient selection. Discuss realistic expectations with your sleep clinician.

Adherence matters: using the machine for fewer than four hours a night is associated with a reduced therapeutic effect in research studies, and greater nightly use is generally linked to better outcomes.^[1] If you are struggling to use the machine consistently, contact your sleep clinic rather than stopping therapy. Common reasons for a lack of response include an incorrect pressure setting, a poorly fitting mask causing leaks, or an unaddressed component of central sleep apnoea. Your clinician can review your machine data remotely in many cases and make adjustments without requiring an in-person appointment.

Driving safety is an important consideration. Excessive daytime sleepiness caused by untreated or inadequately treated OSA can impair your ability to drive safely. You must not drive if you feel excessively sleepy, and you may have a legal obligation to notify the DVLA (or DVA in Northern Ireland). GOV.UK provides guidance on OSA and driving, including when notification is required. Your sleep team can advise you on when it is safe to resume driving once your OSA is adequately controlled.

Lifestyle changes can complement CPAP therapy. Weight loss, reducing alcohol intake (particularly in the evening), sleeping on your side rather than your back, and treating nasal congestion can all reduce the severity of OSA and, in milder cases, may reduce the pressure required from the machine. Discuss any planned changes with your sleep team before adjusting your treatment.

Scientific References

1. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202).
2. Continuous positive airway pressure for the treatment of obstructive sleep apnoea/hypopnoea syndrome (TA139).
3. NG202 Chapter 1: Obstructive sleep apnoea/hypopnoea syndrome — CPAP for moderate and severe OSAHS.
4. Sleep apnoea.
5. Effect of CPAP on Blood Pressure in Patients With Obstructive Sleep Apnea (Martínez-García MA et al.).
6. Effect of CPAP therapy on blood pressure in patients with OSA.
7. CPAP for Prevention of Cardiovascular Events in Obstructive Sleep Apnea (McEvoy RD et al.).
8. Cardiovascular benefit of continuous positive airway pressure according to high-risk obstructive sleep apnoea: a multi-trial analysis. European Heart Journal..
9. Excessive sleepiness and driving.
10. Effect of switching from continuous positive airway pressure to bilevel PAP on aerophagia (Fukutome T et al.).
11. An observational study of 753 cases undergoing CPAP therapy: prevalence and characteristics of aerophagia (Fukutome T et al.).
12. Report a problem with a medicine or medical device (Yellow Card Scheme).

Frequently Asked Questions