Songfacts®:

• Haim spent about two years on the road supporting their 2013 debut album Days Are Gone, which got them in a cycle of soundchecks, shows, sleep and travel. Middle sister Danielle Haim wrote "Night So Long" about the empty feeling that comes with this lifestyle, one that can be hard to grapple with as it's a byproduct of their dream.
  
  She told Rolling Stone: "That came about from being completely alone, with a guitar in a room. Whe we get to play every night, we feel so f--king lucky. But it's isolating too."
• This song took a lot of work in the studio, as its spare, doleful sound isn't typical Haim. They made progress when they decided to keep the song a minimal as possible. Danielle Haim recalled to Pitchfork:
  
  "It's one of the older ones we recorded. It was always just this: a chorus, repeated twice. For a while we wondered whether we should expand on it, or add more lyrics. But in the end, we felt like it was a complete piece on its own. It feels like a hymn."
• Their producer, Ariel Rechtshaid, procured a device called a Quantec QRS that he used on Danielle Haim's guitar for this track. A "room simulator," the QRS was made in the '80s as a way to reproduce the sound of different size rooms with the appropriate reverb.
• Danielle Haim told NPR the composition sat unfinished for years before the band decided to record it.
  
  "We actually wrote this one a long time ago. And it was always just this one thing, a chorus or a verse. We never really throw anything away. But it felt like maybe a chorus. Every time we came back to it we thought it needed another part. But whenever we wrote another part for it it didn't feel right. So it's almost like a hymn with one part repeated. The vocals were done in one take, an old take that I couldn't beat. So we kept it. And then it felt like the last track for the record."
• The song's music video was shot by movie director Paul Thomas Anderson, who previously collaborated with Haim on the visuals for their tracks "Right Now" and "Little Of Your Love". The intimate clip was shot at the Greek Theatre in Los Angeles and changes from a daytime rehearsal to a full night time crowd holding up lights to illuminate the stage.