By research then, you mean direct experience? Observing, interacting?
As a young man I was plagued with OBE'S, sometimes they repeatedly nagged me over and over again, sometimes having multiple OBE'S in one evening. I went to several doctors, Psychologist, and Psychiatrist and nobody had answers for me. Pastors often said it was demonic and that I had demons. And if I remember correctly, doctors basically wrote it off as hallucinations of some sort.
Then one doctor at the VA suggested I go see a parapsychologist. They were the only ones who made sense on OBE'S.
An OBE would begin by me hearing a 'swish' in my head. As those 'swishes' kept coming I often tried to get rid of them by turning on my side in bed etc. One time I let the 'swish' go - and repeatedly saying, "my soul is leaving my body," and it did. I felt myself 'accelerating' and going up a cord. As I went up I could hear a low tone that continually went higher. When the sound reached a very high pitch I heard a 'POP' and I said to myself - wow, I'm here. That's when I did encounter who I believe was a demon. I was facing two double swinging doors. Then I heard a voice behind me saying, "can you hear me". I turned and I saw a man standing there in a long trench coat holding a briefcase. He looked similar to what 'the watchers' always looked like in dreams. I'm looking 'down' at this man. Then he said, "can you see me?" I said yes, I can see you. Then he said, "can you see my face?" Every time I tried to lift my head to see his face, I felt something like a hand on the back of my head pushing my head downward so that I COULD NOT see his face. That scared me and I said, Jesus, please help me!" In less than a second I found myself back in my body - eyes wide open.
Side sleeping prevented most OBE'S - most of the time. If a swish would 'catch me,' I wouldn't be able to move lying there fully conscious - trying to 'snap out of it'. It was scarry and always has been. I have read books about people who dealt with this and one of them lost all fear of it and wow - he had some outrageous OBE experiences. I wish I could remember the name of the book.
At 70 I rarely deal with them anymore.