Lumpy Space Queen

It's a defense mechanism. A holdover from when we were prey. If fight-or-flight is no longer an option, and something is about to harm or kill us, our brains shut down the nerve impulses from our bodies. That way we can't feel it when we're being eaten alive. Dissociation is responsible for out-of-body experiences, near death experiences, astral projection, and a whole slew of other neurological special effects. It can cause memory gaps, too.