"When It's Sleepy Time Down South", also known as "Sleepy Time Down South", is a 1931 jazz song written by Clarence Muse, Leon René and Otis René. It was sung in the 1931 movie Safe in Hell by Nina Mae McKinney, and became the signature song of Louis Armstrong, who recorded it almost a hundred times during his career.[1] The song is now considered a jazz standard and it has been recorded by a plethora of artists.[2] A popular recording in 1931 was by Paul Whiteman and his Orchestra (vocal by Mildred Bailey).[3]