When the hair is loose and down it creates the opposite effect. If the hair is altered on any part of the body it will have an effect on your electromagnetic field. For instance the hair on the legs is there, so that when you walk a charge is created. When hair on the legs is cut it can result in back problems. The pituitary gland and the growth of the eyebrows are related.
Men naturally grow hair there.
Finally, there are spiritual paths that shave their heads and even great spiritual leaders who were bald. Ghandi, Buddhist monks, Dali Lama, etc. The technology of hair and wearing a head covering is just that - a tool. There are many things to do to lead a life of spirit. This is just one thing that we advocate in teaching Kundalini Yoga, because it is what we do and it creates consistency among all 3HO Kundalini Yoga teachers.