I've read up on this specific subject quite a bit on my Psychology course
I can send a copy of the original article if you're interested.
One thing to always bear in mind is that sleep experiments have, on occasion, revealed dreaming in the stages of non-REM
sleep. This could mean that REM
dreams are just more vivid etc.
The thing that will really interest you though is that there's a direct correlation between eye movement and the content of all
dreams (lucid and non lucid). For example in one experiment they recorded eye movement going from left to right, left to right. When they interviewed the guy straght after the REM
stage he said he'd dreamt about watching two people throwing tomatoes at eachother. These same correlations have turned up countless times