Alopecia Totalis is the medical condition that results in hair loss. More specifically, individuals with this condition experience a complete loss of all the hair on their scalp. The onset of Alopecia Totalis can be quite sudden. The primary reason behind this form of hair loss is believed to be an autoimmune response. Where the body's own immune system identifies hair follicles as threats and attacks. Scientists are still trying to figure out the exact reason why some people get Alopecia Totalis. However, things like family, genes, and the environment are known to play a big part.