One of the more common reality checks is plugging your nose and trying to breathe through it.
And if you can, you are dreaming.

Another is closing one eye, and trying to look at your nose with the open eye .
And if you can't see your nose, you are dreaming.

I am wondering why these work the way they do ..

For the first one, i assume it is because you can continue to breathe in real life while in REM sleep. So in a dream, you can breathe fine no matter the circumstances as well.
But that is just a guess. Correct me if i'm wrong.


For the second one. I have no idea why that would work...
How come you can't see your nose when you are dreaming?
What is the science behind that ?