But how does that explain the sleep walking??

Jinwoo was sleepwalking and trying to kill Guwon in his sleep and stuff because deep in the depths of his memories he:

1. Had forgotten his Dad was killed by Guwon.
2. Jinwoo had been through several loops of these same events.

His body was responding to memories Jinwoo was unaware of that lay deep in his subconscious.

If you are confused on Guwon killing the dad I have an in depth explanation under a comment a bit above this one.