Freudian theory gives an answer to that, actually.
because for most humans, the physis force is so great, that even in the unconscious state, death is inacceptable.
That is why you wake up.
Even in dreams, the animal instinct is for life. It rejects death completely and utterly.
One who, in a falling dream, can die, is one who has given up on life.
I've died in my dreams multiple times and continued the dream, but I wouldn't say I've given up on life.
-If anyone has had such a dream, i should like to know. Not dreams about heaven/meeting deceased loved ones, which are common, but has anyone ever dreamt of the exact transition between life and death? when you actually die? (it would completely contravene the life instinct to do so.)
I've had a few dreams like this.
In the first, a man pullled me out of a window on a skywalk, (or whatever you call a bridge that connects two buildings), and I plummeted to my death. The sensation of falling was frighteningly real, and when I 'hit the ground' my vision went black. I could still think, but I was recieving no sense datum. I thought I had died, or was dying. After a moment, stalagtites and stalagmites of swirling color began to grow in my mental image. I thought to myself, "Oh #$%&!, I'm dead! What are these colors? This is the afterlife? WTF!" The spikes of colors continued to grow until they joined together into a unified mass of morphing colors. It was like the visuals you get on an acid trip, only x 1,000. Very slowly, the colors settled down into static shapes and I was in my room.
In the next I was an infantryman surrounded by the enemy in a wooded area. I took my sidearm out, ventilated a few of the badguys, and turned the weapon on myself rather than be taken alive. I stuck the barrel in my mouth and pulled the trigger, but I didn't die. I pulled the trigger twice more and the back of my head popped off like an over pressurized can of soda. I fell to the ground, numb and unable to move, but I could see. The enemy soldiers stood over me, spit on my face, and left. I still couldn't move, and time sped up, and day became night, and night day. Soon, ants and other bugs began to feast on my flesh, and I could feel them crawling all over me, in and out of my ears and nose, eating what remained of my head. I had to get away from the bugs, so I arose and began to wander through the woods, then through a desert, all the while a cloud of bugs following me; I was a walking bug buffet. I came to the edge of a city, climbed a wall into someone's backyard, and laid down next to their pool. A woman walked out of the house and when she saw me this look of horror came upon her. I got on my knees and begged her to let me stay in her yard, where it was clean, but she ran away. I fell back down and my vision turned red, with a picture of a large black bird in flight in the center. Then I woke up.
I've had a few more (the one where I was eaten alive by dogs was particularly gruesome.) But I think two is enough.
edit: has anyone ever had a lucid dream?
I have. When I was in highschool I practiced inducing lucid states. I found I could float, and then fly, and lift things with my mind, or change the forms of things. It was fun, for a while. But I started to hear voices, sometimes they spoke to me, sometimes they would speak only to each other. At first they were friendly, they wanted me to "come with them", whatever that meant. I ignored them, and they grew hostile. Anyway, l started to lose control of these lucid states and they devolved into night terrors. So I stopped.