“One of the other starting points with Sleep was very direct; when our kids were little, I would go off and play a show which would be streamed or on the radio, and Yulia [Mahr, Richter’s wife] would often hear the show in some weird time zone, in the middle of the night. This boundary layer when you’re half-asleep, we started thinking about that as a space for music to happen. Performing Sleep live is kind of like extreme sports,” he added. “I have hundreds of pages of piano music, and it’s a physical challenge. I have to get ‘jetlagged’ so that it’s ‘morning’ when I go on.”

Another contemporary talent who has taken inspiration from sleepless hours is composer/musician Anna Meredith, in her beautifully haunting 2011 work Four Tributes To 4am, based on nocturnal recordings around the city of Derby. “I think I’d read this depressing statistic that more people die at 4am than at any other time,” muses Meredith. “I’ve always found 4am a bit of a ‘no-man’s time’; 3am is like good times from the night before, and 5am might be an early start, but you might not know where 4am fits in terms of yesterday and the next day.

“I had an idea of doing these mini-portraits of what different parts of the town feel like at 4am. My sister [film-maker Eleanor Meredith] and I did an all-nighter, trawling around the dual carriageway with our recorders – the houses, the clubs at the end of the night, the park, the dual carriageway with cars passing by, an out-of-town shopping mall that was totally deserted apart from a few security guards. I remember deliberately slowing the tempo down to create this weighty, unwieldy atmosphere, before gradual awakening in the final movement. You’re awake at this ‘magic hour’ when everyone else is asleep and at their most vulnerable. It feels like you’ve tapped into a secret.”

That sense of discovering secrets and subverting codes is also what makes night music so powerful; we are sleepless but hyper-sensitive – and as Armstrong also notes with his Nocturnes, there is the promise of emerging through the darkness, into a new light.

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