This started as an improvisation by U2 guitarist The Edge, with the others joining in. It was recorded in three takes at Slane Castle in Dublin. The castle on the cover of The Unforgettable Fire is not Slane, but Moydrum Castle.
The lyrics do not specifically mention heroin, but Bono has introduced the song at concerts by saying it is about heroin addiction. A friend of theirs, Phil Lynott from the group Thin Lizzy ("The Boys Are Back In Town"), died after years of heroin abuse in 1986.
Bono watched a lot of teens fall victim to the heroin epidemic in Dublin in the late '70s and early '80s. "They gave up everything they held sacred to this drug," he explained in the band bio U2 by U2. "I tried to describe that with the song, 'Bad,' what it was like to feel that rush, to feel that elation, and then to go on to the nod, the awful sleep that comes with that drug, and then scream: 'I'm wide awake, I'm wide awake, I'm not sleeping!' I can see what's going on."
This is the second song on the album where Bono sings about a heroin addict. The first was "Wire."
This was not a radio hit, but it became a live favorite and a centerpiece at their concerts. The live version on their 1985 album Wide Awake In America helped them gain popularity in the US.
U2 performed a 14-minute version of this song at the London Live Aid
concert in 1985, which included a trip by Bono into the crowd at Wembley Stadium. Their set, which also included "Sunday Bloody Sunday
," was voted Best Live Aid Performance by readers of Rolling Stone
A prerecorded keyboard track was used for live performances to free The Edge up on guitar.
Bono would mix in snippets of other artist's songs when singing this live. He left it alone for the Wide Awake In America recording because he did not want to get sued, as they did with "The Electric Company."
The Wide Awake In America version contains an edit. They screwed up the last note, so a good one from another show was spliced on.
Bono often changes up the lyrics during live performances because he was never satisfied with the song. "That is potentially truly a great song... if I had finished it. And in a way I do finish it every night, live. I change the lyric. Poets have no problem with revising their work. Songs shouldn't be set in stone. If they are any good, they are living, breathing organisms."
Bono: "'Bad' was very difficult to do, almost an impossible collision of cultures for us. It was a different kind of songwriting, like Philip Glass meets Astral Weeks, Van Morrison crossed with German electronica. You have sequences which are rigid and metronomic and then you have a bass which is improvising all the way, and the voice too."