While attempting self-hypnosis as a teenager, I had a weird out of body experience that I don't think that I will ever be able to repeat. I felt like I was floating above my body. I was completely comfortable and lacked any feeling of pressure anywhere on my body. I felt warm like wrapped in a blanket. My mind was devoid of any thought, but I started to become aware that something weird was going on and therefore had a brief instant of panic. It was at that moment I had the sensation of rushing back into my body and I awoke with a start.
I was not dead or dying. I think that I achieved some sort of altered state of consciousness similar to sleep or hypnosis. This has nothing to do with the afterlife.
As I have gotten older, I have been more likely to have states at night where I feel like I am both half asleep and half awake. I have actually had dreams while feeling like I was half awake. Then I wake before falling asleep again.