The yang in the human body mainly plays the role of defense outside the body during the day. In the morning, people's yang is born from the inside and distributed on the body surface; At noon, people are the most prosperous; At night, people's yang enters the room, and the yang on the body surface is gradually insufficient, and the sweat pores are sealed. Therefore, people should refuse at night, don't disturb their bones and muscles, and don't go out to get caught in the fog and dew. If the law of the sun's spiritual movement in the three time boundaries of Japan, China and the West is disrupted, the body will be troubled and infringed by external evils.