Swedish novelist who wrote in the tradition of Social Realism during the 1960s. He also served as a member of the Swedish Parliament (1969–79).

Sundman spent much of his life in the northern province of Jämtland and used that isolated area as a locale for his first book, Jägarna (1957; “The Hunters”), a collection of short stories. It is not incidents or human relationships that are the focus of Sundman's interest so much as the documents the novelist chooses to present to the reader without any accompanying evaluation or commentary. Sundman's radical psychological behaviourism is underscored by a simple, bare style. The purpose of his analytic method is to make the reader aware of the complex and at times incomprehensible nature of truth. In Undersökningen (1958; “The Investigation”) the technique is applied in an investigation of the head of a power station in a poverty-stricken and depopulated area in the northern part of Sweden.

Sundman's most successful novel and the one that brought him the Nordic Council Literary Prize in 1967, Ingenjör Andrées luftfärd (1967; The Flight of the Eagle), is pieced together from the remaining documents of an ill-fated attempt to reach the North Pole by balloon. The analysis of the three main characters in the tragic drama proceeds from the documents themselves with a minimum of artistic ordering. Berättlesen om Såm (1977; “The Story of Sam”) examines the ancient Icelandic saga of Hrafnkel. Sundman's later works include Ishav: isbrytaren H.M.S. Ymers färd i polarhavet sommaren 1980 (1982), which recounts his experiences as part of a scientific expedition in the Arctic Ocean, and the short-story collection Tre berättelser (1987; “Three Stories”).