How Is Sleep Apnoea Diagnosed? Tests, Home Studies and the NHS Pathway

Loud snoring plus daytime exhaustion might point to obstructive sleep apnoea (OSA) — but only a proper assessment can confirm it. Here’s how sleep apnoea is actually diagnosed in the UK, what the tests involve, and what the results mean.

This is general information, not medical advice — start by talking to a GP.

Step 1: See a GP first

The NHS pathway begins with a GP. They’ll ask about your symptoms — loud snoring, witnessed breathing pauses, gasping, unrefreshing sleep, daytime sleepiness — and check things like your weight, neck size and blood pressure. If they suspect sleep apnoea, they’ll refer you to a sleep service (usually a specialist clinic).

Step 2: A sleep test (sleep study)

The sleep service will arrange a test to measure what happens while you sleep. Two main types:

Home sleep test (most common in the UK)

You’re given a small device to wear at home overnight that records things like your oxygen levels, breathing pauses and heart rate. For most people this is the first-line test — it’s simpler and more convenient than a night in a lab.

In-lab sleep study (polysomnography)

Less commonly, you may be asked to stay overnight in a sleep lab, where more sensors (brain waves, eye movement, breathing, muscle activity) are recorded. This is used when the home test is unclear or more detail is needed.

Source: NHS — obstructive sleep apnoea, diagnosis.

Step 3: Reading the result — the AHI score

Results are often summarised as the Apnoea-Hypopnoea Index (AHI) — the number of breathing pauses per hour of sleep. Roughly:

• AHI under 5: generally considered normal (not sleep apnoea)
• AHI 5–15: mild
• AHI 15–30: moderate
• AHI over 30: severe

Your symptom burden matters too — even a “mild” score with significant daytime sleepiness can warrant treatment.

What happens next

If sleep apnoea is confirmed, options depend on severity and symptoms:

• Positional / lifestyle measures (side sleeping, weight loss — gentle cases)
• Mouthpiece (mandibular advancement device) for many mild-to-moderate cases (see our mouthguard guide)
• CPAP for moderate-to-severe cases, or when daytime symptoms are significant

The one-line summary

Sleep apnoea is diagnosed by a GP referral to a sleep service, who usually arrange a home overnight sleep test measuring breathing pauses and oxygen levels, scored with the AHI. From there, treatment ranges from lifestyle changes and mouthpieces to CPAP — so getting an accurate diagnosis is worth it. If you snore loudly and feel exhausted, start by seeing a GP.

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Sources

• NHS — Obstructive sleep apnoea (diagnosis and symptoms): https://www.nhs.uk/conditions/sleep-apnoea/
• NHS — Obstructive sleep apnoea — overview: https://www.nhs.uk/conditions/sleep-apnoea/
• See also our guides: Sleep Apnoea: Early Warning Signs and Ways to Stop Snoring.

This article is for general information and is not medical advice. If you suspect sleep apnoea, see a GP.