Fever
I used to get this weird sensation in my head when I had fever in my childhood. You may call it a natural high. Let me try to describe it as much as I can remember. I could see a part of the wall in the room I was sleeping, but the wall starts to move slowly, at first, moving away from me. The wall accelerates to enormous speed, and places itself to a very large distance away from me. In retrospect, it is just like Starship Enterprise going to Warp 8 from stand still, and going to the other side of the sector. Then, next minutes, the wall comes back to where it was, again, accelerating from standing still to enormous speed. The sensation I felt was a mixture of fear of the speed and fear of being alone in the vastness of space; simultaneously it was strangely exhilarating because of the speed and the vastness of space.
This wasn’t all. A small imperfectly spherical organic object lands on my forehead. The object at times can bounce on my forehead at low speed, much like larva-lamp’s oil goes back and forth between the top and the bottom. And, at times, it speeds up and travel the vast space, as I described for the wall, but this object on return from the trip, it becomes incredibly heavy, and crushing my head. The object can shrink to a very very tiny occupation in space, but kept its heaviness. The object also expands itself in like a balloon, but without a bound. It expands to engulf the size of universe. These motions comes back and forth, as if it had its own life cycle.
My father had always told me the next morning recovering from the fever that I must have had a nightmare. As I got older, I got fewer and fewer episodes, and eventually I lost the sensation nearly all--adulthood takes the romance of pure sensations. We have instead a fear of unpaid bills, and accumulating debt and pressure to perform, etc., becomes your nightmare!
Anyway, yeah, it’s weird!