Overview:Alopecia areata is an autoimmune condition resulting in hair loss. The immune system of the body mistakenly stops hair growth for unknown reasons. Hair loss may be patchy or sparse and may involve the rest of the body in addition to the scalp. Hair in most people spontaneously regrows, though recurrences of the condition are also typical. Genetic and environmental factors play a role in hair loss; the condition may be seasonal as well.