A mate of frontman Mike Kerr's encouraged him to develop this song. He told Kerrang: "We were on tour with a band called Bass Drum of Death and their singer John Barrett is a good friend of ours. One night we were exchanging demos and showing each other ideas we were working on, and I showed him the first idea for this. Initially I wasn't keen on it, but he kinda of convinced me that we should do something on it."
The track has an unexpected influence. "We were going for a Daft Punk thing quite a lot and trying to f--k with the rock thing, I guess," Kerr told NME. "What would Daft Punk do if they wrote a rock tune?"
Mike Kerr sees this as the starting point for the How Did We Get So Dark? album. He told The Sun:
"There were lots of tunes written before this one but when Lights Out revealed itself and came together as a tune, that felt like a breakthrough moment. It felt like we had come up with a tune that had topped anything we'd done before. I guess aesthetically as well - the texture, all the elements of it, the more sophisticated production and the song. That set the tone for the rest of the album."
This was Royal Blood's second #1 on Billboard's Mainstream Rock chart, following "Little Monster" which peaked on the tally in July 2015.
The lyrics for Lesley Gore's "It's My Party" were based on actual events relating to his daughter Judy's sweet 16 party. The teenager threw a tantrum and burst into tears when her mum and dad insisted that her grandparents had to be invited.