>>3403951There's very little difference to how we perceive dreams and reality so there's a need to test it, you don't know if you're dreaming until you wake up. Dreams are quite different from reality, they warp, change, aren't stable at all. If you try reading something in a dream and then try to read it again you won't be able to or you'll get different text, if you will be able to read it at all. Clocks may appear still or going backwards. You might be able to breath while pinching your nose. Performing actions like that in reality and turning them into the habit will allow you to test whether you're dreaming or not and ultimately become lucid. That's reality check.
My reality check is looking at my hands and touching my fingers with my thumbs. In the dreams hands look weird, they can look like hands of dead body, be elongated and fingers might phase through each other, etc. Last night my hands didn't look weird but I could see them from 4 angles at the same time (regrettably that dream was cut short by brief awakening).