Songfacts®:

• "Lights Up" is an enigmatic song about identity in which Harry Styles embraces his true self. He sings on the chorus:
  
  Lights up and they know who you are
  Know who you are
  Do you know who you are?
• The lyrics are cleverly ambiguous, leaving it to the listener to deduce what Styles is saying. We've come up with three possible interpretations.
  
  1. Styles is coming out as bisexual. Rumors of the singer's sexual orientation have followed him for several years but he has consistently rejected labeling himself. Back in March 2018, Styles fueled speculation about his sexuality when he debuted "Medicine" in Basel, Switzerland. One of that song's lyrics seem to be talking about him being with both men and women:
  
  The boys and the girls are in, I'll mess around with them, and I'm OK with it.
  
  Another potential clue is "Lights Up" was released on October 11, 2019. That just happened to be the same date as National Coming Out Day.
  
  The song's music video, which features Styles surrounded by sweat-drenched men and women, gives further credence to this theory.
  
  2. Harry is talking about never returning to One Direction. During the bridge he croons:
  
  Shine, step into the light
  Shine, so bright sometimes
  Shine, I'm not ever going back
  
  Styles may be saying he was in a dark place during his time with the boy band. It's only now that he's a solo singer that he feels he's able to be his true self. The track also invokes an atmospheric '70s soulful vibe, suggesting he is distancing himself from his former pop persona. However, the biggest clue lies in the two verses where each time he makes an apology:
  
  I'm sorry by the way
  Never coming back down
  
  Harry could be saying sorry to the One Direction fans knowing they will be heartbroken he's not returning to the group.
  
  3. Harry is talking about the toxicity of being a celebrity. "All the lights couldn't put out the dark," may be a reference to how fame was not able to shield him from the darkness dwelling in his heart; instead it acted as a smokescreen. It was only when Styles started living his life away from the cameras that he was able to locate his sense of self.
• Styles wrote the song with:
  
  His frequent collaborator Tyler Johnson, who contributed to all 10 tracks on Styles' eponymous debut album. An associate of American producer Jeff Bhasker, Johnson has also worked on artist projects for Ed Sheeran, Taylor Swift and Keith Urban.
  
  Kid Harpoon, who was Styles' songwriting partner on his single "Sweet Creature." The English singer/songwriter has contributed to several of Florence + the Machine's hit singles, including "Shake It Out," "Never Let Me Go" and her hook-up with Calvin Harris, "Sweet Nothing."
  
  Johnson also takes sole credit for producing the track.