Thanks for the replies.

I'll check out that link more thoroughly over the next few days, thanks, Paigeyemps.

Could you describe them more? How does it happen for you? I don't think WILD is something you can do without trying.
Well, they are a more recent occurrence and it'll sound dumb! But I have a new cat which insists on being let out at 6am. I try to ignore it but it will just jump on my head until I get up and let it go outside. I usually do this in a very sleepy state and when I get back in bed I feel a sort of 'heaviness' in my head and I hear muffled voices as I'm drifting off, and sometimes see imagery. I've actually talked to doctors about this because I thought I was going mad. Of course, they all dismiss it as some phenomena that doesn't really mean anything. But after coming back to bed I tend to have my best lucid dreams. If I don't like the dream I am able to pull myself back into awakening (which takes a bit of effort).
I have had this experience before without the cat, LOL. Usually when a loud noise or someone abruptly wakes me before it's time to get up and I drift back into sleep.

But, as I said, I have been doing a lot of research over the last year-ish, so maybe on a subconscious level I know what is happening and allow it. But I've never "tried" to do it, it just happens.