NEW YORK, N.Y. (WPVI) --The CPAP machine has become the standard treatment for many of the 25 million people with sleep apnea.
But there's evidence it may not help some as much as doctors thought.
CPAP machines are still beneficial.
However, for years, doctors had thought they'd help prevent heart attacks in all people with sleep apnea.
The new study, conducted in 7 countries around the world, says that's not the case for people who already have heart disease.
The finding surprised even the scientists at the Australian research institutes doing the research.
CPAPs help keep your airway open when you sleep.
It prevents people with sleep apnea from stopping to breathe.
In this study, patients who already have heart disease had the same rate of future heart attacks, with or without CPAP.
But they still got some important benefits.
Those include less snoring, less daytime sleepiness and better moods