I once heard from a "dream expert" that we dream every night.
It's just that sometimes we can't remember any of them.
But I went through and sometimes go through times were I don't recall having any dreams what so ever. And coincedentally, I noticed that I too don't have any dreams when my insomnia kicks in....
And then there's times when the only dreams I have are nightmares....
Trippy shit, but I found that the more sleep you get, the less nightmares, sleep paralysis, and no dream nights you get....