CPAP Explained: How It Works
What is CPAP? It is continuous positive airway pressure: a small machine that gently pushes air through a mask to hold your airway open during sleep. It is the first-line treatment for obstructive sleep apnoea, prescribed by a sleep clinic after a sleep study. An app cannot diagnose apnoea or prescribe CPAP.
If a sleep clinic has mentioned CPAP, it can feel daunting. The machine looks medical, and you may worry about sleeping with a mask. Here is what CPAP actually does, who needs it, and what to expect in plain English.
What is CPAP and how does it work?
CPAP stands for continuous positive airway pressure. It is a quiet bedside machine connected by a tube to a mask you wear over your nose, or your nose and mouth, while you sleep.
In obstructive sleep apnoea (OSA), the soft tissues at the back of the throat relax and collapse during sleep, briefly blocking breathing again and again. CPAP works like an invisible air splint. The steady stream of pressurised air keeps the airway propped open, so the pauses stop and your sleep is no longer fragmented.
Who needs CPAP?
CPAP is prescribed for people with diagnosed OSA, usually moderate or severe. OSA is graded by the apnoea-hypopnoea index (AHI), the number of breathing events per hour of sleep. Mild is 5 to 14, moderate is 15 to 30, and severe is over 30. Only a clinical sleep study can measure this and confirm the grade.
You cannot self-prescribe CPAP. It follows a referral from your GP to a sleep clinic, then a sleep study. If loud snoring, breathing pauses, or daytime exhaustion sound familiar, that is the path to discuss. See the symptoms of sleep apnoea and learn how AHI grades severity.
What should you expect from CPAP?
Realistic expectations help. Here is the honest picture.
| What people ask | The reality |
|---|---|
| Does it work? | It is the most effective OSA treatment and substantially cuts tiredness-related crash risk. |
| Is it easy to stick with? | Adherence runs about 30 to 60 percent. The first few weeks take adjustment. |
| Are there alternatives? | For mild to moderate OSA, a mandibular advancement device may be offered. |
The early nights are the hardest. Mask fit, pressure and humidity often need tuning, so stay in touch with your clinic rather than giving up.
CPAP treats apnoea, not simple snoring. If your snoring is the main issue, tracking it for a week with Kip gives you loudness and frequency trends to bring to your GP. Kip is a wellness and screening tool. It flags patterns consistent with disrupted sleep and cannot diagnose anything.
Sources
- NHS: Sleep apnoea
- NICE NG202: Obstructive sleep apnoea/hypopnoea syndrome
- Tregear et al: CPAP reduces motor vehicle crash risk in OSA
FAQ
Can I buy a CPAP machine without a prescription?
CPAP is prescribed by a sleep clinic after a sleep study confirms OSA and its severity. The pressure setting is tailored to you, so it is not something to self-prescribe. If you suspect apnoea, see your GP for a referral.
Why do people stop using CPAP?
Adherence is around 30 to 60 percent, often because the mask feels uncomfortable, the pressure is hard to get used to, or the nose dries out. Most of these are fixable with mask changes, humidification or pressure tuning, so tell your clinic before giving up.
Is CPAP the only treatment for sleep apnoea?
No. CPAP is first-line and most effective, but for mild to moderate OSA a sleep clinic may offer a mandibular advancement device, weight loss support, or positional therapy. A doctor decides what suits your case, not an app.