Marie Antoinette syndrome, also known as Canities subita or Thomas More syndrome, is a rare condition where hair suddenly turns white overnight due to stress or trauma. The name alludes to the unhappy Queen Marie Antoinette of France, whose hair allegedly turned white the night before her execution. The syndrome has been hypothesized to be a variant of alopecia areata diffusa or autoimmune non-scarring hair loss that selectively affects all pigmented hairs, leaving only the white hair behind. It is caused by high levels of emotional stress, which, in turn, causes less pigmentation of the hair. Although a rare event, it has affected well-known historical figures, including Sir Thomas Moore and Queen Marie Antoinette of France. It has been found that some hairs can become colored again when stress is reduced.