While these were not technically NDE's, it definitely opened up for me the possibility that an NDE is potentially possible and that more research should go into this.
I remember looking around the room and I could see myself and my wife asleep. It didn't register to me at that time, that I was looking at myself from outside my body. It felt like a dream and I didn't have any desire to try to fly around or through anything, I was content to float there and observe.
About a minute or two into the experience, I noticed something crawling across my pillow, towards my head. As I focused on it, it appeared to be a spider. This made me panic. I think the panic wasn't because of the spider, but that I suddenly realized I was floating in the air and looking at myself. I was overwhelmed with fear and felt myself suddenly fall into my body, at which point I woke up immediately. There was a physical sensation of light pressure when that happened. That experience felt like it lasted only a few minutes.
I jumped out of bed, turned on the some lights and looked all over. I pulled the blankets off the bed, turning over my pillow, etc. I woke up my wife and told her there was a spider on the bed. We spent a few minutes trying to find it, but to no avail. I never had anything like that happen before or since.
I don't know what actually happened, but the experience felt very real. There wasn't any alcohol or drugs involved, but I was in the Air Force at the time, so it could have been aliens. ;-)
Could the whole thing have been a dream?
Even if you remember waking up before it happened, that doesn't mean that it was not a dream. You can have a dream within a dream, or have two consecutive dreams that make you feel like you dreamed within a dream.
It can be scary because we're essentially confronting the unknown, but concentration helps with that. Fear is a distraction that takes you away from a single pointed mind. When you recognize fear or worry popping up, you gently return to your object of concentration until it goes away.
However, you will often project things onto the environment subconsciously, so it may not be exactly in line with the physical world.
It's like there is a description of the world there that we can access, but we can also overlay our own constructs on top of that description. An unbridled mind fills the environment with seemingly random imagery and we experience dreams, but a concentrated mind sees the environment itself.
It's really not much different from being awake actually - sometimes you're fully aware of your concrete surroundings and other times you're lost in abstract daydreams, completely oblivious to what's going on around you.
As for "looking" at yourself, I usually wouldn't see my body, but I'd feel a strong magnetic pull coming from that area of the room. If I got too close, I'd get sucked into my body and wake up.
I believe data about the physical world is available during an out of body experience, but it's impossible to be entirely objective about it since, whether in the body or "outside" of it, we have no choice but to access that data through a mental construct, i.e., an experience.
I would probably dismiss it all as a dream state too, if not for the experiences I had - including really impossible stuff, like seeing future events.
You can certainly have conversations with other beings there, although I don't think there's a good way to discern the nature of those beings. They are intelligent anyway.
Some people view sexual energy as a fundamental power that can be used for a variety of spiritual purposes, so they suggest that it be sublimated or transmuted.
Maybe these things seem weird - and they are weird - but neither proves that the world experienced while "out of body" is fabricated by the brain, assuming that's what you meant by dream-type state of course.