When is it okay to fall asleep in a theatre?
Ahead of a new play that actively encourages the audience to fall asleep, its cast - and other stars of the stage - reflect on those moments when applause sometimes turns to snores.
Imagine the scene. Hamlet has launched into his most famous soliloquy.
"To sleep, perchance to dream..."
And there in the front row of the stalls, someone is slumped in their plush velvet seat doing exactly that.
It's just such an awkward moment that helped inspire a new show called Lullaby, by theatre company Duckie, which opens at the Barbican next week.
Theatre-goers bring their pyjamas and a toothbrush (and possibly a teddy bear) and watch the performance from the comfort of a luxury bed in the auditorium.
After an interval in which you clean your teeth and go to the loo, it's back to bed to be lulled by music and a parade of dream-like animals.
The show ends when the last audience member falls asleep - with breakfast served next morning.
Lullaby is devised by four performers - Harriet & H Plewis, Tim Spooner and Matthew Robins - and directed by Mark Whitelaw.
"We conceived it as a Dada-esque, Dali-esque dream-world for adults," says Harriet Plewis, when we met during rehearsals in east London.
Each performance takes place in front of 50 beds - singles, doubles and triples. But the cast is keen to stress that there are no jokes played on the sleeping audience.
"It's about trying to give people a good night's sleep. It really is a tender, loving show - because we do see it as quite a responsibility," says Harriet.
The show's code of conduct includes a strict "no hanky-panky" rule.
"We don't want to deny excitement," says Harriet's sister, and co-performer, H. "It's not about controlling people.
"Even though we're saying no hanky-panky, there's going to be a natural excitement about sleeping in a theatre with 50 other people."
Lullaby, she says, is a natural response to shows that set out to shock. "We've experienced an overload of irony in theatre and culture in general over the last few years and this is a reaction to that."
So how widespread is the problem of punters nodding off in the theatre?
"Even in a wonderful performance of a great play I'd say there will be five people asleep at any one time," says Dominic Cooke, artistic director of the Royal Court.
"One thing I always do is have the auditorium as cold as humanly possible to stop that from happening."
Geraldine James, currently in Chekhov's Seagull at the Arcola, says: "It is so soul destroying for an actor."
She blames in part the "corporate nature" of the West End with business visitors who are "brought in by the busload".
Theatre design can be responsible too: "That proscenium arch and that orchestra pit and those hot plush velvet seats and too may gin-and-tonics is deadly."
Doctor Who actor Arthur Darvill, in Dr Faustus at Shakespeare's Globe, recalls working on a two-hander at the Edinburgh Fringe when he was fresh out of drama school.
"My co-star had a walking stick throughout the whole show - so when a gentleman fell asleep in the front row he got prodded with it."
Lullaby performer H admits she's guilty of falling asleep in the theatre too. "It's the darkness, the warmth and the quiet that induces it - more than what's on stage."
So will Lullaby be a show without any applause at the end?
"A snoring ovation," says Harriet. "That's what we'd like."
Lullaby is at the The Pit, Barbican from 24 June - 24 July.