★★★★☆

In 2015, German-British composer Max Richter released his most ambitious work to date, an eight and a half hour composition designed to be listened to while sleeping. Natalie Johns’ documentary on the piece is an appropriately languorous, dreamy exploration of Richter’s music taken at its own pace and pleasurably in thrall to its subject.

After a career balancing commercial and artistic pressures – the latter subsidising the former – Sleep is Richter’s attempt to resolve both. Written with the knowledge that most of it will not be consciously heard by its audience, Sleep is a highly-conceptual piece but it is also about a fundamentally universal human experience while the music itself is by definition as comforting as a warm blanket.

Less successful, perhaps, is the segment dedicated to Richter’s career and his ambition in composing and performing his music. It feels schematic and odd to frame such a conceptual piece with such a straightforward narrative, especially given that the family story it presents is dully conventional. Richter satisfied assertions that he ‘bet the farm’ on financing the piece are infinitely less interesting than the segment dedicated to the vocal-straining, finger-blistering labour that his musicians provide to execute it.

Johns has structured her film fairly conventionally, overlaying talking-head interviews with footage of its live performances. These segments give us intriguing nuggets of information, for example that Richter worked with neuroscientist David Eagleman so that his music would mimic the brain’s patterns while sleeping. But Sleep the film is at its strongest when it lets Sleep the music speak for itself – the outdoor footage of the performance in Los Angeles’ Grand Park in particular is haunting, moving stuff.

There is an eerie calm to the images of hundreds of people serenely dreaming in the open. Richter’s steeped melodies gently wash away the direct questions that documentaries customarily ask in favour of unconscious contemplation and reflection. Normally, a viewer’s wandering mind would indicate the failure of a documentary to hold the attention; here it is a veritable measure of its success.

Watching the Grand Park footage may be a poor simulacrum of the real thing, but as Richter’s piano laps at the edges of the film and Grace Davidson’s ghostly soprano blankets itself across the park’s immaculate lawn, it’s hard not to feel some soothing approximation of the live experience. Max Richter’s Sleep succeeds best in these moments, when it lets its audience forget the quotidian whys and hows, and drift into the space of its subject between waking and sleeping, where conscious experience meets unconscious sensation.

Max Richter’s Sleep is out now in cinemas and on demand. maxrichtersleep.co.uk

Christopher Machell | @MachellFilm