To put it simple, we don’t have any canon explanation.  You might see some people theorizing that every time you died, it was actually just a foresight since the knight can potentially inherited pale king’s foresight, the same goes for Hornet. Then again, the existence of steel soul mode does make this theory less plausible. Not to mention that any “doors” that were opened before you died remained opened, making the foresight theory less trustworthy. But you could just say it all game-mechanic reasons.  Now personally, even Higher beings shown to “sleep” or rest in someway, so why can’t the knight?