Not just in surgery for example but in extreme other situations (nukes, titan sub, piano to the head, etc)... You're just there then you aren't and you don't even know. Shook me (lightly) for a while
I'm guessing being properly flattened by a truck is similar, though of course that's adjacent to being severely injured and dying later.
Interestingly some medications like tadalafil restore my dreams... My smart watch also tells me the phases like remand deep have normal lengths. So I'm not sure why it is so rare for me to dream, but I suspect low glucose or oxygen may have something to do with it.
You might be having those but “not having dreams” is not an indication of that. And i put the “not having dreams” in quotes because for most people they have dreams but then go on to forget them.
If you are having other symptomps by all means get it checked out. But if your only symptom is not remembering dreams i wouldn’t worry about that.
One may think, any existence is better than nothing.