"Sleepwalker" is a song that Finnish symphonic power metal quintet Nightwish made and performed during the national Finnish Eurovision Song Contest tryouts in 2000. Although they placed first in the Finnish televote, the jury overruled them, selecting Nina Åström instead.
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 and the special version of the "Bless the Child" single.
A line from the song ("end of innocence, unending masquerade") was later reused as the title of the 2003 Nightwish DVD End of Innocence.
The line "Silently the senses, abandon all defences" is most likely straight from the song "Music of the Night" from Andrew Lloyd Webber's The Phantom of the Opera. The main theme of the musical was later covered by the band on their 2002 album "Century Child".