I have to temp vaginally because I sleep with a cpap machine that causes really irregular oral temps. I have my alarm set for 5am on my phone every day, I temp and record it on my phone then fall back asleep most of the time. The only sucky part is temping on the weekend when I don’t have to be up that early, to wake up to temp anyway.

Some do it vaginally if they are having trouble see the shift. Usually those that sleep with mouth open do it vaginally since it affects readings. I only temp from a few days before I ovulate (I’m regular) and until I can confirm ovulation then I stop. But not vaginally.

Yep some do if they are a mouth breather when they sleep. If you know you sleep with your mouth closed, it’s fine to use your mouth.