Not sure. People who practice. To practice impurity meditation means to be vegetarian all year round. Keep your body and mind pure and recite the Buddha's name. Nature has this light like a relic. glow. Ordinary people can't see it. Someone with this kind of light. While sleeping in the mountains, snakes, rats, insects and ants. Everyone will see it. It will also go away automatically. Because they are most afraid of this kind of light.