For sleep apnea you may look into playing the didgeridoo for 30 minutes a day. The circular breathing every day really improve people's symptoms, and I've heard you see results after a few weeks or months. I'm in the middle of trying this but unfortunately I just haven't been doing it every day.

I've also heard just practicing circular breathing by blowing through a straw into a cup of water can produce the same effect but playing a didge is just so much cooler.