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Overview - Obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is quite common. It is a condition where the walls of the throat relax and narrow during sleep. This interrupts normal breathing.

It can lead to regular interrupted sleep. This can have a big impact on your quality of life. It increases the risk of developing certain conditions.

Types of obstructive sleep apnoea (OSA)

There are 2 types of breathing interruptions of OSA: apnoea and hypopnoea.


This is when the muscles and soft tissues in your throat relax and collapse. They do this enough to cause a total blockage of the airway. It's called an apnoea when your airflow is blocked for 10 seconds or more.


This is a partial blockage of the airway. It causes a reduction in your airflow of more than 50% for 10 seconds or more.

You can have more than 1 episode of apnoea and hypopnoea throughout the night. They can happen once every 1 or 2 minutes in severe cases.

Obstructive sleep apnoea-hypopnoea syndrome (OSAHS)

You can have episodes of apnoea and hypopnoea. This is called obstructive sleep apnoea-hypopnoea syndrome (OSAHS).

OSAHS is different from rarer forms of sleep apnoea. For example, central sleep apnoea. This happens when the brain does not send signals to the breathing muscles during sleep.

Content supplied by the NHS and adapted for Ireland by the HSE

Page last reviewed: 22 December 2020
Next review due: 22 December 2023

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.