He was born in
Kristiania (now Oslo), Norway. He was the son of Hans Hegna (1863–1945) and Birthe Buttingsrud (1876–1956). He attended
Oslo Cathedral School. He studied economic and social economics at the
University of Oslo where he became
Cand.philol. in 1923. When
Mot Dag was dissolved in 1936, Hegna again became a member of the Norwegian Labour Party. Between 1939 and 1940 he was the editor of
Vestfold Arbeiderblad, and in 1940 he became editor of
1ste Mai (now
Rogalands Avis) in
Stavanger. During the
Occupation of Norway by Nazi Germany, the newspaper was closed after publishing the headline "Ingen nordmann til salgs!" (No Norwegian for sale!). In September 1940, Hegna was arrested and imprisoned in
Grini concentration camp until 1943. After the liberation of Norway at the end of
World War II, he again became editor of
1ste Mai, a position he held until 1958. He was a member of
Stavanger city council from 1945 to 1955, and was represented at the
Storting between 1950 and 1965, for a period leader of the Standing Committee on Finances and Customs . He was in the national board of the Labour Party between 1949 and 1953 and deputy chairman of the party group at Stortinget from 1958. Hegna was one of many
Mot Dag members that became influential in the Labour Party after the second world war, but in a contrast to many of these, Hegna was active in the left wing of the party, among other things against Norwegian membership in the
European Economic Community in 1972, but he chose to remain with the party. Hegna also wrote several books, among these books about the
Soviet Union, about
genealogy, and also served as a translator of
fiction books. In 1983 he published the autobiography
Min versjon. ==Personal life==