The song was released in two different versions, the "normal" version and the "heavy" version. The "heavy" version was slightly different, both in the use of instruments and Tarja Turunen's vocals being softer and not so very operatic. "Sleepwalker" appeared on the limited edition of the 2000 album "Wishmaster" and the 1997-2001 4 CD Box Set. The "heavy" version can be found on the "Deep Silent Complete" single, the "Wishmastour 2000" compilation, the special version of the "Bless the Child" single, and on the 2CD+DVD edition of "Highest Hopes".
A line from the song ("end of innocence, unending masquerade") was later reused as the title of the 2003 Nightwish DVDEnd of Innocence.