Herrgård was the first Swedish celebrity with Acquired Immune Deficiency Syndrome to go public about it, "giving Acquired Immune Deficiency Syndrome a face". Sighsten Herrgård received his fashion education at Beckmans School of Design in Stockholm and at the pattern development academies in Stockholm and Copenhagen. In the 1970s Herrgård established internationally in Paris and North America.
He also started a company in Stockholm and worked with television, magazines and shows.
On 29 July 1987 Herrgård held a press conference, stating that "I"m going to die. I have Acquired Immune Deficiency Syndrome. I may only have months left, but I want to die with dignity".