Alopecia Areata
This type of hair loss is believed to be caused by the immune system reacting to hair follicles as if they were antibodies and shutting them down. The hair loss is usually limited to a coin sized area and all the hair in the area is lost leaving a totally smooth round patch. In a more severe rarer condition called Alopecia Totalis, all hair on the entire body is lost, including the eyelashes. Treatments include topical medications, a special kind of light treatment, or in some cases drugs.