The Three-Minute Nose Test
A guided three-minute test that decides whether your nasal airway is reliable enough to consider sealing your mouth at night. It is the screening step almost everyone skips.
Mouth taping is only safe if the other airway works. Sealing the mouth above an unreliable nose removes your backup route without fixing the primary one, and it is the one genuinely risky version of this whole category.
The test is three minutes, sitting still, awake. If you cannot do it conscious, you should not be doing it asleep.
Sit somewhere comfortable before you start. A timer will run for three minutes, and you can stop it at any point.