Is there any way to prove your whole life has not been a dream? Even if your whole life had been a dream, how would you know? What if your dreams are simply dreams within a dream? In The Matrix, Morpheus asks "How would you known the difference between the dream world and the real world"? If you feel similar to Alice tumbling down the rabbit hole, you're not alone. In "Tumbling Down the Rabbit Hole Knowledge, Reality, and the Pit of Skepticism," Matt Lawrence calls this hole the pit of skepticism.
Descartes conclusion was there was no way of being absolutely sure that he was not dreaming. 'Reason' was the foundation of his pursuit of the 'true and certain' axiom, "I think therefore I am." In Meditations on First Philosophy, Descartes wrote,
"How often, at night, I've been convinced that I was here, sitting before the fire, wearing my dressing gown, when in fact I was undressed and between the covers of my bed!... I see so plainly that there are no reliable signs by which I can distinguish sleeping from waking that I am stupefied-and my stupor itself suggests that I am asleep!"
While you may not know the answer to the initial question that was posed, you can follow your curiosity at the individual level. If you can remember a dream, as far as your brain is concerned, it really happened. You will typically only remember the last one or two dreams and sometimes, your brain will put two dreams together. Begin by writing down what you can remember from your dreams after you wake up. See if you can find any personal archetypes in them after. Check out the movies "DMT: The Spirit Molecule" or "Inland Empire" for more exploration.
Dream counselor Cliff Hamrock states if you go long enough without sleep, you will become paranoid and start to hallucinate. The most important thing to know about sleep is you need it. Your brain even knocks you unconscious, so it does not have to deal with your body. One part of your mind knows you are unconscious while the other part paralyzes you. Sleep paralysis is when you are conscious that you are paralyzed. Sleepwalking is when you are unconscious, but not paralyzed. Society values productivity and we grow up to see sleep as waste of our time. Without sleep, however, we are irritable, depressed, and we can't form memories.
Our imaginations are more active at night. Dreams happen during rapid eye movement (REM) sleep. During this stage, your frontal lobe actively draws connections and pattern. When you are awake and in problem solving mode, you are in beta stage. While dreaming, our subconscious comes out to play in metaphors because the static from beta waves is turned off and we can attune to different things than when we are awake. While dreams may only be brain dumps, but let us consider a different theory. What if our brain is not only a physical organ, but also a spiritual organ where dreams are a portal for spiritual inclusion?