--
[0] - somehow they exist and they don't use it as a personal holodeck to escape reality, which tells me lucid dreaming must be overrated.
I've had over 100 lucid dreams, although none recently. My crowning achievement was summoning Socrates that would teach me things using the socratic method (only asking questions). The thing that blows my mind today is I was able to take away real value from these conversations even though I supplied both the questions and the answers.
Why didn't I use it as a personal holodeck to escape reality? Reality is a bigger, more interesting, and more exciting place than inside my own head.
Not surprising - whenever we think, we supply both inputs and outputs ourselves :).
If I had that level of vividness of dreams and I could make them lucid, I'd definitely want to sleep more than I do now, to push experiments such as yours to sleep time. I mean, from what I read about lucid dreams, in best cases you have enough control over it that you could essentially use it as a sandbox prototyping environment!
Lucid dreaming is actually a skill anyone can learn.
Edit: Now that I think about it, the population is probably less than anyone. Anyone that can get a goods night rest can learn how to lucid dream, and anyone that routinely enters REM sleep has a decent shot at it.
I really, really, really wish vividness of mental images would be trainable. I so want it.
Color is rare. I mostly don't even notice in most dreams except a very few where it's central, like the one time I saw a colorful dreamcatcher-like crystal mobile-thing after waking from a dream and enjoying still having it from my dream, only to wake up and realize that they were both dreams. Doh!
I keep believing I can learn to visualize based on the fact that seeing is hallucinating. We take samples of light and imagine that we're actually seeing the world when really we're guessing that's what it is and synthesizing what we see. A great example of this was when I came back from a tropical vacation and back in the city a leaf blew past my feet. I swear I clearly saw a small lizard (like I'd testify that I saw a glimpse of one) as I had been seeing for the past few weeks. I saw the leaf on the second glance. So if I can conjure a lizard, I can draw some cylinders and wires eventually.
My internal audio reproduction seems to be quite good (which would be great if I could remember more music, or at least whole songs, to play on my internal jukebox :/ - sometimes I do remember more when dreaming). I think recall/visualization/etc. is affected by limited working memory capacity and how working and long term memory interact; I suspect that is often the major limitation when awake also and would still apply to some extent when asleep (although things can clearly work somewhat differently when asleep).
I do believe that a majority of people can visualize fairly easily since it seems like most people can describe the appearance of someone they just met when not looking at them, which I am unable to do (most days). Yes there are non visual tricks to do that, but it does seem like many people do that type of thing effortlessly and also for things they are less likely to have previously learned tricks about. When I do know someone better I seem to be better able to recognize their distinctive style of movement than most people.
Dreaming is strange... lately I haven't been wanting to be aware of my dreams at all since I often end up with events looping while I am increasingly paralyzed (and of course everyone else want me to do something). I've noticed this seems more likely to happen on days I take baclofen (as a help stay asleep sleep aid), but it happens at other times also and happened occasionaly before I ever took baclofen.
Well it worked for Socrates in that way too - he just happeed to be awake :)
Maybe you're blessed with effortlessly getting enough of it, which in case congratulations. A lot of the people around you are not.
One thing I'm not saying is you should maximize sleep. Just get enough, and get good quality. Maybe that's our misunderstanding.