Lex thought that he would barely nap for half an hour, or that if he entered deep sleep he'd be out for a couple of hours at most. He couldn't be blamed for thinking as such because lately he would sleep very less unless he was injured and using his recovery techniques.
Even though, right now, he was technically injured, he did not plan on using any recovery techniques, so he planned on only passing a few hours at most. Unfortunately, due to the fact that none of his pain receptors were working, and his incredible physique allowed him to function normally, he underestimated how injured he really was.
That was not to mention that any time he was injured, his spirit was injured as well, which really affected his decision making skills. It was the most significant flaw of his cultivation technique. Though to be fair, Regal Embrace was on the path to ensure that he never got hurt in the first place. Now though, the end result would be up to his own efforts.
