From what I've read of the J-Wiki writeup on "Nemurenu Yoru", this song seemed to have paralleled its lyrics in terms of Off Course's career trajectory. The producer of the band's 3rd album that included it, "Wine no Nioi"（ワインの匂い...The Bouquet of Wine), Toshi Buto（武藤敏史）, came to the conclusion that up to that point in Off Course's repertoire, there was a distinct lack of simple songs, and just songs that people could enjoy. He made that point abundantly clear to Oda, who had originally made "Nemurenu Yoru" into a ballad, and ultimately the leader saw the light and changed the arrangement. It was a good tip by Buto since the song in its new form became the band's first decent hit, peaking at No. 48 on Oricon.
Off Course's 7th single was released in December 1975, at the same time as the album.