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Causes - Obstructive sleep apnoea

During normal sleep, the muscles and soft tissues in the throat relax and collapse. For most people, this does not cause breathing problems.

If you have obstructive sleep apnoea, your airway narrows while you sleep.

Why your airway narrows

Obstructive sleep apnoea can be more common if you are:

  • carrying extra weight
  • male
  • over 40

It is also linked to:

  • neck size and structure
  • family history
  • nasal congestion
  • menopause
  • medicines
  • alcohol
  • smoking
  • high blood pressure
  • asthma

If you are carrying extra weight

If you are carrying extra weight, the fat around your neck can put a strain on your throat muscles.

Too much stomach fat can put pressure on your lungs. This can lead to breathing difficulties and increase your risk of sleep apnoea episodes.

How to eat well

If you are male

Obstructive sleep apnoea is more common in men. This may be linked to differences in where body fat is stored.

Over 40

Obstructive sleep apnoea can happen at any age. But it's more common in people who are over 40.

Neck size and structure

Men with a collar size of more than 43cm (17 inches) have a greater risk of developing obstructive sleep apnoea.

You are also at risk if you have:

  • a narrow airway
  • large tonsils, adenoids or tongue
  • a small lower jaw

Family history

You may inherit genes from your parents that increase your risk of developing sleep apnoea.

Nasal congestion

If you have nasal congestion, you are more likely to develop obstructive sleep apnoea. Long-term congestion can happen if you have a deviated septum. This is where the tissue between your nostrils is bent to one side.


Your hormone levels change during menopause. This can reduce muscle tone in your throat, and lead to obstructive sleep apnoea.


Some medicines can cause your airway to narrow. For example, sleeping tablets or tranquillisers.


Alcohol can narrow your airway. This is more likely if you drink alcohol before going to sleep. This can make you snore more and increase your risk of sleep apnoea episodes.

Alcohol and health


You're more likely to develop sleep apnoea if you smoke.

Stop smoking

Types of obstructive sleep apnoea

There are 2 main types of obstructive sleep apnoea:

  • apnoea
  • hypopnoea


Apnoea is when your airway is completely blocked for 10 seconds or more.


Hypopnoea is when there is a partial blockage of your airway. You have about half your normal airflow for 10 seconds or more.

These blockages happen when the muscles and soft tissues in your throat relax and collapse in a way that limits your breathing.

You can have more than 1 episode of apnoea or hypopnoea during the night. In severe cases, you can have episodes every 1 or 2 minutes all night.

Obstructive sleep apnoea-hypopnoea syndrome

You may have both apnoea and hypopnoea. This is called obstructive sleep apnoea-hypopnoea syndrome.

Other types of sleep apnoea

There are other less common types of sleep apnoea. One example is central sleep apnoea. This is where the brain does not send signals to the muscles that control breathing while you sleep.

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

Page last reviewed: 13 September 2023
Next review due: 13 September 2026

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