However, no one who has slept with me has ever said I sleep with my mouth open. And my sleep doc said I did not sleep with my mouth open during the sleep study. Nevertheless, I wonder just how open your mouth has to be in order to be a mouth breather. Does it have to be gaping so it looks like you're trying to catch flies? What if my mouth is just open a tiny bit - enough to cause the leaks but not visible on a video recording?
Several months ago, at Zonk's suggestion, I finally broke down and bought a chin strap from my local DME. Because my leakage problem is mostly due to movement around the bed I wear it over the mask. It's function is not just to hold the mouth shut but also to keep the mask in place. The chin strap from the DME has no brand name or identification on it, but it looks a bit like the Chin Strap - Deluxe SKU AG302425 on Supplier #3's web site, except that it also has a strap around the back. It's basically elastic bandage material. This chin strap has worked reasonably well for me, but there are problems: 1) about once a week I wake up in the middle of the night and the strap has come off and, 2) it has become horribly filthy and no amount of washing or bleaching will get the grime out of it. Nevertheless, using this chin strap I was able for the first time to get my leaks regularly under 24L.
About a week ago I started using a Ruby chin strap, mostly on the recommendations here and also on the reviews at our suppliers' sites. Man, I just cannot get that thing to fit on my head! For the past week my maximum leaks have never been below 35L and 95% never below 24L. It is the most uncomfortable thing I have ever had on my head, pinching me in places I was not designed to be pinched. On a positive note, it has not shown any dirt yet.
I'm giving up on the Ruby, but I need other ideas. I need a chin strap that has no hard parts to pinch me in the middle of the night, can be slipped on over the head without having to undo the adjustments, has enough straps placed strategically so that I can't dislodge it and, doesn't cover my ears. Does anyone make a chin strap like that?