For basic evaluation of sufficient daytime breathing, pulse oximeter would likely be the tool to start with, not a PAP machine.
Many professionals and hobbiests and trained athletes have to be taught to learn to be mindful of their breathing when they hit the zone. Weight lifters, for example, are notorious for pausing their breathing inappropriately.
Concentration is a good thing. But try your best to keep your shoulders relaxed and let the tension in your body go, even when you have your game face on.
No need to
worry about daytime breathing, though, since that would likely add to the stress instead of releasing it. No pressure; just in and out.
End of my Captain Obvious commentary.
Meantime, I guess you could always adopt this song by Wheat as your theme song:
