Obstructive Sleep Apnoea Test: UK Guide

An obstructive sleep apnoea test is the essential step in confirming whether repeated airway collapse during sleep is disrupting your breathing and health. OSA is a common but frequently undiagnosed condition that causes fragmented sleep, excessive daytime sleepiness, and long-term cardiovascular risk. In the UK, testing ranges from a simple overnight oximetry clip worn at home to a full in-laboratory polysomnography study. This article explains how OSA is diagnosed, which tests are available on the NHS, what to expect during a home sleep study, and how your results will guide treatment decisions.

What is obstructive sleep apnoea and how is it diagnosed?

OSA is diagnosed by combining clinical assessment, validated questionnaires such as STOP-Bang or Epworth, and objective sleep testing to calculate the AHI. Objective testing is required to confirm the diagnosis; questionnaires alone are insufficient.

Obstructive sleep apnoea (OSA) 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. These episodes reduce oxygen levels in the blood, fragment sleep, and leave the person feeling unrefreshed in the morning. OSA is more common in people who are overweight, have a large neck circumference, or have anatomical features that narrow the airway, though it can affect people of any body type.^[5]

Diagnosis is based on a combination of clinical assessment and objective sleep testing. A clinician will typically ask about symptoms such as loud snoring, witnessed apnoeas (pauses in breathing noticed by a bed partner), excessive daytime sleepiness, morning headaches, and difficulty concentrating. Standardised questionnaires such as the Epworth Sleepiness Scale help quantify daytime sleepiness, and structured risk tools such as STOP-Bang or OSA50 may also be used to guide triage.^[8][2] These tools support clinical assessment but do not diagnose OSA on their own; objective sleep testing is required to confirm the diagnosis.

OSA is classified by severity using the Apnoea-Hypopnoea Index (AHI), which counts the average number of breathing interruptions per hour of sleep. NICE guideline NG202 defines mild OSA as an AHI of 5 to 14 events per hour, moderate as 15 to 29, and severe as 30 or more.^[1][2] Where home oximetry or respiratory polygraphy is used, UK services may also use the Oxygen Desaturation Index (ODI) alongside or instead of AHI to grade severity. Severity guides treatment decisions, so accurate testing is essential before any management plan is put in place.

What tests are used to check for sleep apnoea in the UK?

The main tests are home limited channel sleep studies and in-laboratory polysomnography, with overnight oximetry used as an initial screening tool. NICE NG202 supports home-based testing for most straightforward adult cases.

The main tests used to diagnose obstructive sleep apnoea in the UK are limited channel home sleep studies (sometimes called respiratory polygraphy) and in-laboratory polysomnography (PSG), with overnight pulse oximetry used as an initial screening tool in some services. NICE guideline NG202 supports the use of home-based testing for most adults with suspected OSA, reserving full in-laboratory PSG for cases where the diagnosis remains uncertain or where other sleep disorders are suspected.^[1][2]

A limited channel home sleep study typically records airflow, respiratory effort, oxygen saturation, heart rate, and body position. It does not measure brain activity, so it cannot stage sleep, but it provides enough information to calculate the AHI and confirm a diagnosis in the majority of straightforward cases.

Overnight pulse oximetry measures blood oxygen saturation continuously through the night using a small probe worn on the finger. It is less detailed than a full sleep study but can identify patterns of repeated oxygen desaturation that are characteristic of OSA. It is important to note that a normal oximetry result does not reliably exclude OSA when clinical suspicion is high; in such cases, a more detailed sleep study should still be considered.^[2][5]

Full polysomnography is conducted in a specialist sleep laboratory and records brain activity (EEG), eye movements, muscle tone, airflow, respiratory effort, oxygen saturation, and heart rhythm simultaneously.^[5] It is the most comprehensive test available and is used when the clinical picture is complex, for example when narcolepsy, periodic limb movement disorder, or parasomnias are also suspected alongside OSA.

How do I get tested for sleep apnoea on the NHS?

The first step is a GP referral to a specialist sleep service, which will typically arrange a home sleep study in line with NICE NG202. Waiting times vary by NHS trust and Integrated Care Board.

To get tested for sleep apnoea on the NHS, the usual first step is to speak to your GP, who will take a history, assess your symptoms, and refer you to a specialist sleep service if OSA is suspected. Your GP may ask you to complete the Epworth Sleepiness Scale before or during the appointment, and may also check your blood pressure, weight, and neck circumference, as these are relevant risk factors.

Following referral, most NHS sleep services will arrange a home sleep study as the initial investigation, in line with NICE guideline NG202. Waiting times vary between NHS trusts and Integrated Care Boards (ICBs), which commission local sleep services. In some areas, a GP can initiate overnight oximetry directly before a formal sleep clinic referral, which can help speed up the diagnostic pathway, though this varies by ICB.

Driving safety and DVLA notification: If excessive daytime sleepiness is affecting your ability to drive safely, you must stop driving and notify the DVLA. You should follow your doctor's advice on when it is safe to resume driving. Failing to notify the DVLA when a medical condition affects fitness to drive is a legal offence.^[6][7] If you are unsure whether your symptoms affect your driving, speak to your GP.

If you prefer not to wait for an NHS referral, or if you would like to explore your options more quickly, private sleep assessment services are available. Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online consultations with prescriber review, and clinicians there can advise on appropriate next steps for sleep-related concerns where clinically relevant. It is also worth noting that some conditions associated with OSA, such as obesity, may be addressed through weight management pathways, and your GP can advise on whether these are appropriate for you.

If your symptoms are severe, for example if you are falling asleep at the wheel or experiencing significant cardiovascular symptoms, contact your GP urgently or call NHS 111 for advice on how quickly you need to be seen.

What happens during a home sleep study or overnight oximetry test?

A home sleep study records airflow, respiratory effort, oxygen saturation, and pulse rate overnight using equipment worn in your own bed. The test is non-invasive and most people complete it without difficulty.

During a home sleep study, a sleep technician or nurse will show you how to set up the recording equipment before you take it home, or in some services a postal kit is sent with written and video instructions. The equipment is worn overnight in your own bed, which means the results reflect your normal sleeping environment rather than an unfamiliar hospital setting.

A typical home sleep study kit includes:

• A nasal cannula or thermistor to measure airflow at the nose and mouth (the specific sensor used may vary between services)

• Effort belts worn around the chest and abdomen to detect breathing movements

• A finger probe to record oxygen saturation and pulse rate

• A small recording device clipped to clothing or placed on the bedside table

You will be asked to go to bed at your usual time, sleep as normally as possible, and return the equipment the following morning. The device records data automatically throughout the night, and you do not need to do anything once it is set up correctly.

For an overnight oximetry test, the process is simpler: a small clip-on probe is placed on one finger and records oxygen levels and pulse rate throughout the night. It is lightweight and most people find it easy to sleep with.

Neither test is painful or invasive. Some people find the nasal cannula mildly uncomfortable, but the majority complete the study without difficulty. If the equipment falls off during the night or the recording is of poor quality, the sleep service will usually arrange a repeat study rather than making a diagnosis on incomplete data.

What do my sleep test results mean and what happens next?

Results are reviewed by a specialist who calculates your AHI to determine OSA severity and guide treatment. CPAP is recommended for moderate to severe OSA, while mild OSA is initially managed with lifestyle measures and possibly a mandibular advancement device.

Your sleep test results will be reviewed by a specialist, usually a respiratory physician, sleep physician, or a trained sleep physiologist, who will calculate your Apnoea-Hypopnoea Index and interpret the oxygen saturation data alongside your symptoms. An AHI below 5 events per hour is generally considered within the normal range in adults, though symptoms and clinical context are always taken into account.^[2][5] Where oximetry or respiratory polygraphy has been used, the ODI may also inform the severity assessment and management decision.

If OSA is confirmed, the severity will guide the treatment recommendation:

• Mild OSA (AHI 5 to 14): Lifestyle measures are usually the first approach, including weight management, reducing alcohol intake, avoiding sedatives, and sleeping on your side.^[10][2] Mandibular advancement devices (custom-fitted dental splints) may also be offered.^[2][10] CPAP therapy can be considered in mild OSA if symptoms significantly affect quality of life despite other measures, or if a mandibular advancement device is unsuitable, in line with NICE TA139.^[3][4]

• Moderate OSA (AHI 15 to 29): Continuous positive airway pressure (CPAP) therapy is typically recommended alongside lifestyle advice, in line with NICE TA139.

• Severe OSA (AHI 30 or above): CPAP is the standard treatment and is strongly recommended. It involves wearing a mask connected to a small machine that delivers a gentle stream of pressurised air to keep the airway open during sleep.

CPAP is highly effective when used consistently, and most people notice a significant improvement in daytime alertness and quality of life within a few weeks. Your sleep service will provide the equipment, fitting support, and follow-up appointments to optimise the pressure settings.

If your results are borderline or your symptoms do not match the AHI, your clinician may recommend a repeat study or a full in-laboratory polysomnography. If you drive and your sleepiness is due to OSA, you must follow DVLA guidance: stop driving until your condition is adequately controlled and notify the DVLA as required. You should contact your GP or sleep service if your symptoms worsen or if CPAP is not improving your symptoms as expected.

Scientific References

1. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202) – Overview.
2. NG202 Chapter 1: Obstructive sleep apnoea/hypopnoea syndrome.
3. Continuous positive airway pressure for the treatment of obstructive sleep apnoea/hypopnoea syndrome (TA139).
4. TA139 full guideline PDF – Continuous positive airway pressure for the treatment of obstructive sleep apnoea/hypopnoea syndrome.
5. Sleep apnoea.
6. Telling DVLA about a medical condition or disability.
7. Check if a health condition affects your driving: Overview.
8. Daytime sleepiness, snoring, and obstructive sleep apnea: the Epworth Sleepiness Scale. Johns MW. Chest. 1993..
9. Use and Performance of the STOP-Bang Questionnaire for Identifying Obstructive Sleep Apnea. Pivetta B et al. JAMA Network Open. 2021..
10. NG202 full guideline PDF – Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s.
11. Meta-analysis of randomised controlled trials of oral mandibular advancement devices and CPAP for obstructive sleep apnoea-hypopnoea. Sharples LD et al. Sleep Medicine Reviews. 2016..
12. The effect of CPAP therapy on excessive daytime sleepiness and quality of life. Venkatnarayan K et al. 2021..
13. CPAP therapy for excessive daytime sleepiness and quality of life in OSA. McNicholas WT et al. The Lancet Respiratory Medicine. 2023..

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