Hair in religion also plays an important role since women and men, when deciding to dedicate their life to faith, often change their haircut. Catholic nuns often cut their hair very short, and men who joined Catholic monastic orders in the eighth century adopted what was known as the tonsure, which involved shaving the tops of their heads and leaving a ring of hair around the bald crown. Many Buddhists, Hajj pilgrims and Vaisnavas, especially members of the Hare Krishna movement who are brahmacharis or sannyasis, shave their heads. Some Hindu and most Buddhist monks and nuns shave their heads upon entering their order, and Korean Buddhist monks and nuns have their heads shaved every 15 days. Adherents of Sikhism are required to wear their hair unshorn. Women usually wear it in a braid or a bun and men cover it with a turban.