So far the nights I've slept with it on my mouth, I wake up with less mouth irritation and pain

Still trying to heal this mouth, which is like nursing a wounded lamb back to health. It's going well at least!

My friend who lives in Ireland is also trying the same technique of duct tape.

As a general rule, I wake up with the tape still intact. Depending on how I'm sleeping that is. I have taken the tape off my mouth in my sleep before.

Friend did suggest a tape that breathes a bit more (can be bought at the drug store I believe) that holds just as well, so I may have to look into that one! I think it's a cloth based tape v whatever duct tape is, plastic? LOL.