Immortals, neither sleep nor eat.
Even though Nezha's cultivation is only at the God Absorption Realm, when his body is filled with Heaven and Earth Primordial Qi, he can also replace eating and sleeping with meditation.
When Nezha first entered the God Absorption Realm, he tried this; for approximately three days, he neither ate nor slept. Initially, he felt a bit sleepy and hungry, but by the second day, once his body began to adapt, he gradually got used to this feeling.
This involves the law of energy conservation; since the minor internal cycle connected with the major cycle of the world, sustaining life shifted from taking in water and food from outside to absorbing the Heaven and Earth Primordial Qi into the body to maintain bodily consumption.
Since it was okay not to eat, Nezha felt more like a plant capable of photosynthesis.
