I have, at times, been able to lift myself up from pain, to disassociate myself from it, almost Zen-like, I suppose. I use both physical and mental tools to do this. Of course I can't, always, make it work. But I think our bodies work with us in this respect, that they rush endorphins to the rescue when greater levels of pain cannot be endured. In a prolonged torture like Jesus' I would expect to become "spacey" after a while.
So I think about it. I think, Jesus wanted to be conscious so he could bear more.
At the same time I think he could be "above it", take as much as they could give. He would not be calling on God to save him from pain, but instead calling from within himself to be able to endure more.
Clearly, being present for all of it would have the greater impact if you believe he is doing it for you. On the other hand, accepting it all with the strength borne of belief has to mean something too.