When the Buteyko theory is applied to breathing, there seems no reason why almost everyone cannot breathe quietly and regularly through their nose, just the way they did when they were born.
While it is acknowledged that either lengthy or very frequent apnoeas are not healthy, and the evidence that having sleep apnoea is linked to some serious health issues, the Buteyko theory is more interested in the snoring.
The snoring is seen as an abnormal way to breathe, and unless the person had a cold, it would normally be the sound of hyperventilation during sleep. It is possible to hyperventilate during sleep without making the snoring sound, but it is probably difficult to make the snoring sound without breathing too fast or too vigorously.
Since there is a strong connection between snoring and OSA, with the person snoring for a number of years before the apnoea starts, it seems logical to stop the snoring and see if this helps the problem.
Learning to reduce the automatic breathing pattern while you are awake helps to reduce the automatic breathing pattern while you are asleep. The Buteyko method has been shown in two clinical trials to reduce the automatic breathing pattern by an average 31%, which lead to a reduction of asthma symptoms by at least 71%.
No clinical trials have been done with the Buteyko method and sleep apnoea, but there is no reason from the Buteyko point of view why the person who has any hyperventilation problem, such as snoring, would not reduce their symptoms to a similar degree. Every week in Buteyko classes, people are reporting this very thing.
While you are waiting to enrol in a Buteyko course, take a look at snoring solutions.