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Obstructive sleep apnoea (OSA)

What is obstructive sleep apnoea (OSA)?

Obstructive sleep apnoea (OSA) is a breathing problem that happens when you sleep. On this page, we explain what OSA is.

When we sleep, our throat muscles relax and air flows freely to our lungs. If you have OSA, your throat closes completely and the flow of air stops, so you stop breathing for a short time.

OSA disrupts your sleep, making you sleepy during the day. If it’s not treated, it can have a big impact on your life. And if you don’t get help, it can have a big impact on your health too. We know lots of people go undiagnosed. But the good news is there’s effective treatment. If you want to find out more for yourself, or this sounds like someone you know, read on.

On this page:

What is OSA?

It’s called obstructive sleep apnoea (OSA) because:

Obstructive: there’s an obstruction in the airway

Sleep: it happens when you’re asleep

Apnoea: it means you stop breathing for a short time

If your throat closes completely when you sleep, you stop breathing for a time. It’s called an apnoea if it lasts for 10 seconds or more. If the airways in your throat narrow, this is called a hypopnoea. When this happens, there may be a dip in the level of oxygen in your blood.

Your brain will start your breathing again. Some people wake up briefly, but others are not aware of what’s happening. Breathing often restarts with a gasp or grunt and some movement. You relax again, and the pattern then starts again.

If you have severe OSA, this cycle can happen hundreds of times a night. These frequent arousals disrupt your sleep and so you can feel very sleepy during the day. Some people with OSA are not sleepy but can experience tiredness, fatigue, sleep disruption or even insomnia.

Diagram - Air travelling freely through the airways


In normal breathing, air can travel freely to and from your lungs through your airways during sleep.

 

 

Diagram - air cannot pass through the collapsed airway


In OSA, your airway collapses, stopping air from travelling to and from your lungs, stopping your breathing for a short time and disturbing your sleep.

 

 

Who’s more likely to have OSA?

You’re more likely to have OSA if: 

  • you’re a man and middle aged
  • you’re a woman past menopause
  • you’re a woman in the later stages of pregnancy -  OSA symptoms often improve or disappear after your baby is born
  • you are overweight or obese 
  • you have a large neck size - 17 inches (43 cms) or more
  • you have a small airway, a set-back lower jaw or a small lower jaw, large tonsils, a large tongue or nasal blockage
  • you have a medical condition that makes some of these factors more likely, such as Down’s syndrome
  • you have type 2 diabetes
  • you have a chronic heart disease.

OSA can also be made worse by drinking alcohol, using sleeping pills and smoking.

I snored very loudly, and I would stop breathing. It had a major effect on my ability to think clearly at work. Brenda

Next: What are the symptoms of OSA?

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Last medically reviewed: November 2021. Due for review: November 2024

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.