Is "florid dreams" a thing (Google didn't come up with anything meaningful)? Did you mean lucid dreams (though for the life of me, I can't understand why that wouldn't be welcomed).
I don't know the term either, but I experience what the parent poster said. I've tried melatonin, and it gives me crazy vivid dreams that keep up the feeling of stress. It doesn't rest the brain, it's more like being knocked out by concussion, and it takes hours to reset and wake up and get back to functioning.
No, it's not a thing, its a term my partner used. Lucid dreams you have (within limits) control over the narrative, florid dreams she described as hyper-real, disturbing and unwelcome.
"vivid dream melatonin" had heaps of hits. "melatonin nightmares" might be another way of putting it.
