With his current cultivation, sleeping, eating, and breathing, the normal bodily functions weren't as important anymore.
He didn't need to eat anymore as, as long as he cultivated, the energy was enough to keep his body moving, of course, if the meal was a Qi nutritious meal that was something else, altogether.
Sleeping was even more useless, to him, as he didn't need to sleep anymore, and just meditating for a few hours was enough for him to regain his freshness.
Breathing was not as advanced though, even though his skin did more of breathing for him, and he needed to breathe only once in 5 minutes, it was still something he had to do.
If he wanted he could go for about 20 to 30 minutes without breathing, while blocking any possible way, but that was only for emergencies', and it wasn't like it wasn't much of a hassle for him.
