A kind of inner spirit like one's subconscious that supposedly leaves and comes back to one's body while sleeping. Some believe that it leaves if one doesn't eat dinner. Some believe that a person can't remember his dream if his lihan has left his body while he's sleeping. Some believe that when the lihan leaves the body, a person can fall asleep and when he returns the person can wake up.
According to traditional beliefs, if we haven't eaten at night, our inner spirit will leave and go wandering around.