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What CPAP does, and what it has not been shown to do

CPAP is the main treatment for obstructive sleep apnoea. The research supports some claims about it and not others.

What a large review found

In 2019 the American Academy of Sleep Medicine reviewed the trials of CPAP and similar machines in adults with obstructive sleep apnoea. Compared with no treatment, it found meaningful improvements in:

  • how severe the sleep apnoea was during the night
  • daytime sleepiness
  • sleep-related quality of life
  • blood pressure
  • motor vehicle accidents.

The same review found that self-adjusting machines did no better for patients than standard CPAP, and that starting treatment at home worked as well as starting it in a sleep lab.

What one large trial did not find

The SAVE trial followed 2,717 adults with moderate or severe sleep apnoea who already had heart disease or had had a stroke. After nearly four years, CPAP had not reduced heart attacks, strokes or other cardiovascular events. It did reduce snoring and daytime sleepiness, and improved mood and quality of life.

One limit of that trial: people used their machine for an average of only 3.3 hours a night.

What this means for you

CPAP is prescribed after a diagnosis. How much it helps differs from person to person, and it only works on the nights you use it. If the mask or the pressure bothers you, tell whoever supplies your machine. A different mask or setting is a common fix.

How Breathe fits in

We rent CPAP machines by the week, help fit your first mask and check in on how it is going. See sleep tests and CPAP.

This page is general information, not medical advice. Your doctor or nurse knows your situation; please talk to them before changing any treatment.

Sources

  • Patil SP and others. Treatment of adult obstructive sleep apnea with positive airway pressure: systematic review and meta-analysis. Journal of Clinical Sleep Medicine, 2019. doi.org/10.5664/jcsm.7638
  • McEvoy RD and others. CPAP for prevention of cardiovascular events in obstructive sleep apnea (the SAVE trial). New England Journal of Medicine, 2016. doi.org/10.1056/NEJMoa1606599
  • Health New Zealand. Obstructive sleep apnoea. healthnz.govt.nz

Checked November 2026. Airline and official pages change, so follow the links for the current wording.