It is certainly a Biblical and Classical view that there are levels of reality and even our waking state can be called a dream , as in:
Peace, peace! he is not dead, he doth not sleep— He hath awakened from the dream of life— 'Tis we, who lost in stormy visions, keep With phantoms an unprofitable strife...
You can't even ask the question unless you at least theoretically allow that there might be something besides whatever you term 'dreaming'. You can tell the difference between being thirsty and dreaming of drinking a lot of water and when you wake up you are still thirsty and drink real water. You know the difference then
But all in all this is a case of playing with your own sanity
Charles Sanders Peirce — 'Let us not pretend to doubt in philosophy what we do not doubt in our hearts.'