Obstructive sleep apnoea (OSA)

What is obstructive sleep apnoea (OSA)?

Obstructive sleep apnoea, or OSA, is a breathing problem that happens when you sleep. It can affect anyone – men, women or children.

When you’re asleep, your throat muscles relax. In some people, a narrower airway means they snore. But if your throat closes completely, you stop breathing for a time. For some people this happens throughout the night and it’s called OSA.

OSA disrupts your sleep, making you sleepy during the day. So if it’s not treated, it can have a big impact on your life – you might feel exhausted when you’re awake, and you might doze off at any time – so it’s not safe to drive for example. And if you don’t get help, it can have a big impact on your health too.

We know that lots of people go undiagnosed. The good news is that there is effective treatment.

What does OSA mean?

It’s called OSA because:

Obstructive: there’s an obstruction in the airway of your throat
Sleep: it happens when you’re asleep
Apnoea: this means you stop breathing

What happens when you have OSA?

When you go to sleep your muscles relax, including those in your throat. In some people the relaxing muscles cause the airways to narrow, which can reduce the amount of air flowing in and out of your airways. This makes you snore.

If your throat closes completely, you stop breathing for a time. This is called an apnoea if it last 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.

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



In OSA, your airway collapses, stopping air from travelling to and from your lungs, disturbing your sleep.


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Last medically reviewed: May 2016. Due for review: May 2019

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.