Why do we shave the head

Why the Hindus shave the hair off their heads at places like Tirupathi.? Why do Muslims wear topi(cap) and Sikhs wear pagdi.? Hair represents Tamas (sloth/lethargy). In fact tamas is represented by the color black. To progress spiritually, one has to give up tamas via rajas (passion, intensity, action and energy) and then move to sattva before going beyond the gunas (attributes) to become one with the divine. Therefore, to remind one that giving up tamas or sloth is the first step in spirituality, the hair is either shaved off or covered with a skull cap. Om Sai Ram.