Mostly, my dreams are very bizarre. Sometimes hilariously so. Oh! Just last week, I woke up laughing from a kind of dream within a dream. In it, I was describing a dream while walking with someone. They said something really bizarre in response, then I bounced off that with something so funny I burst out laughing and it woke me up. (Yeah, I'm funny even in my sleep!

Oh, wait, I mean "easily amused".

)
Sometimes disorientingly bizarre. Or just plain terrifying. Which tend to come in spells. A couple that readily come to mind actually meant something. Strangely enough, one was nothing if not my subconscious screaming "bipolar!", illustrated with flying (and
not at all the super fun type of flying dreams I had as a kid). No plane, just me zooming WAY too high (plus I'm scared of heights), followed by sudden screaming sonic-speed nosedives, repeated endlessly, complete with physical sensations of falling and abject terror. In it, I had no control what.so.ever. It was f'in terrifying. Here's the thing. When those were happening, I didn't know BP from diddly and had no idea what the deal was with them. Years later it struck like a lightning bolt. Duh!
Other terrifying ones seem to have themes such as "lost and alone in a very scary place". Others feature violence or the imminent threat thereof, precipatating waking terrorized in a cold sweat and a sensation like... you know that lurch feeling looking down from a height? That. Teamed up with whole body uber-tension and it won't stop for quite some time. Paranoia and heightened vigilance of where I actually am in reality at the time too. Fear of going back to sleep? YES. Actually, it's fear of going back to the nightmare. Plus fear of letting my guard down because of oogidy-boogidys near at hand (see: paranoia).
The only pattern I've been able to discern at all is stress, but it doesn't seem necessarily so. If there is a particularly bad run going on, it definitely creates apprehension over going to sleep. Haven't found anything to ward them off, though I would be inclined to knock myself the flip out(!) to try. My son used to have night terrors when he was a kid. Not sure what my deal is, but I think it's just straight up nightmares. I do have spells of incredible hypnopompic hallucinations, which have nothing to do with any of this, just part of my sleep-world.
But VIVID whether bizarre, perplexing or terrifying? OH YES.