I have noticed that I have two types of dreams that do not involve any imagery.

Sometimes I have dreams which just consist of conversations between 2 or 3 people. Upon waking it is very hard to remember much of the wording. (A recent dream had 2 people talking about elements of normal dreaming and lucid dreaming, and how the elements worked in each. For example gravity - awake this didn't really make sense as gravity fails for me in both NDs and LDs)

In other dreams there is only one voice talking about something, like a dream lecture.

With both these types of dreams, I'm never sure if I'm missing out on usefull information, or just gibberish. (one dream lecture had something about downstream loss of signal consciousness, leading to normal dreams rather than lucid dreams).

Do you have dreams like this? Do you think they are non-REM dreams?

In one dream conversation I became lucid. That stopped the conversation, and I was just in an empty space with no dream body or imagery. I tried to visualize and wait for images, but eventually I moved one finger and awoke.