"Subspace" - does it actually exist?

It's talked about a lot at times and to tell the truth I've always found it fascinating. So what is it?

From my experience (observing sub females) there appears to be two specific types of subspace:

1) When someone is edging on their limits they suddenly become almost languid and vague in their reactions. The effect of painful stimuli is dulled and their pupils become fully dilated. Seems almost like they're in a post orgasmic haze or have drunk too much wine!!
2) When someone is experiencing an orgasm after a painful or intense session they suddenly "lose" themselves i.e. they're no longer aware of where or who they are and have to be "brought back" gently. This is a much stronger reaction than they would normally have. In contrast to the above their pupils contract to pin-pricks.

Obviously everyone is different and I've only seen these effects in some people. I presume both are altered states triggered by an endorphin rush. Are these examples of subspace?

Those I've asked have described the experience very differently - some say it's amazing, seeing rainbows, fields, coloured rain (!) etc whereas others have said it can be frightening and disorientating.

I'd like to ask - how do we think it actually works? Does pain, pleasure or a combination of the two open the door? And finally - whats it like when you're actually there?

YNHumiliator

"...a friend who bleeds is better."