Shanti Kaur Khalsa explains why Sikhs don't cut their hair. Cutting the hair is one of the co-rehets, meaning Guru Gobind Singh commanded that Sikhs shouldn't do it. The hair (kesh) is also one of the 5 k's. The hair channels spiritual energy in action, which helps people in the householder lifestyle. There are also traditions where people shave their heads completely. This makes the spiritual energy go internally.
