Diagnosing Obstructive Sleep Apnoea (OSA)

Who is at risk?

Although OSA can affect anyone, certain factors increase the likelihood of developing the condition. You may be at greater risk if you:

  • Are overweight or obese
  • Are male
  • Are older, as risk increases with age
  • Have a family history of OSA
  • Have a naturally narrow airway, retrognathia (set-back lower jaw), enlarged tonsils or adenoids, or a larger neck circumference
  • Regularly consume alcohol or take sedative medications, particularly before bedtime
  • Have medical conditions such as high blood pressure, type 2 diabetes, heart disease, certain hormonal disorders, or have Down Syndrome

Importantly, OSA can also occur in people who are young, female, or not overweight. The absence of risk factors does not exclude the possibility of OSA.

When should you seek medical advice?

You should speak with your healthcare professional if you have loud snoring (or it’s not possible to say as you don’t have a witness to your sleep), plus symptoms such as:

  • Pauses in breathing during sleep
  • Waking up gasping or choking
  • Excessive daytime sleepiness or fatigue
  • Waking up with a headache
  • Poor concentration or memory problems

If you have one of these symptoms you may not need a sleep study.

Just listen
Do you or a member of your family sound like this when asleep?

Obstructive Sleep Apnoea (OSA) is suspected based upon your symptoms, medical history and physical examination. Validated questionnaires may be used:

If OSA is suspected, your healthcare professional may arrange a sleep study (respiratory polygraphy). This is a simple test that monitors your breathing while you sleep and records information such as:

  • Breathing patterns
  • Blood oxygen levels
  • Heart rate
  • Sleep position
  • Snoring

Not everyone will need a sleep study but if you do have a sleep study, the results help confirm whether OSA is present and determine its severity.

Understanding OSA severity

The severity of OSA is measured using the Apnoea–Hypopnoea Index (AHI), which calculates the average number of breathing interruptions (apnoeas) and partial airway blockages (hypopnoeas) per hour of sleep. Sometimes it is calculated using a measure called the oxygen-desaturation index (ODI), which calculates the number of dips in blood oxygen levels per hour, which is gives similar information to the AHI.

Severity                    AHI (events per hour)

Normal                       Fewer than 5

Mild OSA                    5–14

Moderate OSA           15–29

Severe OSA                30 or more

Early diagnosis and treatment can improve sleep quality, reduce daytime symptoms, and help lower the risk of long-term health complications associated with untreated OSA.

You can print a patient information sheet and take to your GP if you think you have OSA.

The BBC produced an article (with video) in January 2026: I snore – but didnt’ know I stop breathing 10  times an hour in my sleep .

We also publish a range of informative leaflets including What is Obstructive Sleep Apnoea .

If you are awaiting a Sleep Study to confirm diagnosis of Sleep Apnoea or have been newly diagnosed, the information on our website will help you understand the diagnostic process and treatment. It does not replace the guidance and advice you should seek from your Medical Professional. The Glossary of Terms may help you understand some of the words that may be used and frequently asked questions may also be helpful.

NHS treatment for people from abroad

NHS treatment for people from abroad has changed since leaving the EU, so please refer to this NHS link to find out whether or not you may be charged.

Driving and Sleep Apnoea

Sleep Apnoea may affect your ability and eligibility to drive. The authority on driving in the UK is the DVLA whose website should always be consulted for the latest position But a more understandable interpretation of the rules can be obtained here.

References:

  1. American Academy of Sleep Medicine (2023) The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications. Version 3. Darien, IL: American Academy of Sleep Medicine.
  2. Johns, M.W. (1991) ‘A new method for measuring daytime sleepiness: the Epworth Sleepiness Scale’, Sleep, 14(6), pp. 540–545. doi:10.1093/sleep/14.6.540.
  3. National Institute for Health and Care Excellence (NICE) (2021) Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202). London: NICE. Available at: NICE Guideline NG202 (Accessed: 5 June 2026)

 

Last updated on 24 June 2026
Written by Jennifer Troath, Advanced Clinical Physiologist in Respiratory and Sleep Medicine, AHCS Registration No. 69167
Volunteer Clinical Adviser, Sleep Apnoea Trust
With input from Claire Allen, Annabel Nickol and Chris Turnbull (Sleep Apnoea Trust).