Interesting that you mention the rollercoaster part. A couple of years ago, I was lying in bed, pretty relaxed with my eyes closed when I felt a huge surge of white light. Even with my eyes closed, all I could see was white as I recall and I felt like I was on a rollercoaster, it was pretty fun, but, eventually it stopped. I opened my eyes and I was still in my room I'm starting to think that my case like yours was an accidential WILD(in my case), although I think you were closer than me at having a LD, GL