Songfacts®:

• Part of King Diamond's horror-rock concept album Conspiracy, "Sleepless Nights" picks up a storyline from the previous album, Them, where King's sister Missy is killed. In this track, King is at a graveyard trying desperately to connect with Missy and pleading with the spirits, who he calls "Them."
  
  It became one of Diamond's most popular tracks, and one that can work independently of the concept, since the theme of being haunted at night is common.
• King Diamond's guitarist Andy LaRocque wrote the music for this song. In our interview with LaRocque, he explained that the guitar riff was inspired by a 1978 Black Sabbath song called "Air Dance."
• The music video did well on MTV's metal show Headbanger's Ball, which helped King Diamond get exposure in America (the band is Danish). The video shows a coffin that is attended by Franz Harary, a magician who developed a coffin trick that became part of the group's stage show. Harary, known for a televised stunt where he made the Space Shuttle disappear, had developed the coffin bit and sold it to King Diamond. The stunt has developed over the years, but the idea is that King Diamond or another character get in the coffin, it is set on fire, and then opened up to reveal either nothing or a charred corpse.