What's an artist to think when his audience goes to sleep?

I went to a concert in Aldeburgh last week at which, at one point, roughly a quarter of the audience around me was asleep. It wasn't at all a bad concert - an East European string quartet playing Haydn, Shostakovich and Beethoven. But it had been a warm day, and what with the sea air and the lull of the Snape marshes and a glass or two of white wine beforehand and then the gentle sawing of bows and the opportunity for those in the uncrowded promenade area to stretch out and just close their eyes a moment...

Apart from a few embarrassing episodes (the worst of them sleeping through the long-awaited first television showing of The War Game), I'm not a great nodder-off myself. And one of the advantages in staying awake for concerts, plays and operas is that it allows you to observe those who don't - the discreetly snoring bourgeoisie. Some sleepers are prodded awake at regular intervals by companions with sharp elbows; a few are unreachable until the final curtain. When people speak of having "a good night out", this probably isn't what they mean. But it comes to the same thing: an evening's culture, perchance to sleep.

There is nothing new about this Rip Van Winkle Syndrome. Haydn was conscious enough of it to plant a fortissimo chord in the slow movement of his Surprise Symphony. He made it loud enough to wake the dead - a composer's jokey revenge on those not listening carefully enough. The best lecturers, too, know that it pays them to employ shock tactics, having learnt the hard way that there is nothing more sleep-inducing than the sound of a single human voice. At the new Globe, there's been an attempt to recreate audiences that are, as Shakespeare's were, noisily irreverent and alert. But for two centuries the norm has been sedentary and sedate: after-dinner audiences sleeping what Orwell called the deep, deep sleep of England.

What strikes me about the 1990s is just how many people are using culture to get themselves a good kip. Harassed at the office, stressed out at home, insomniac with anxiety, they book themselves a comfy seat in the dark - and let their worries slide away. Naturally, they don't put it to themselves like this. Few theatregoers feel affluent or shameless enough to spend pounds 20 simply in order to drop off. Nor do box offices, so far as I know, recommend particular seats in the stalls or dress circle on the grounds that they're the best ones to sleep in. Still, on any evening in the West End you're bound to encounter a good number of dossers. Some complain they are a public nuisance. But so long as they don't snore loudly in the wrong places, they're tolerated.

Sleep, like sex, is supposed to cost nothing, but it isn't always easy to get and some are willing to pay for it rather than go without. Snoozing at the office is socially unacceptable. Dropping off at the dinner table may give offence, at any rate before coffee is served. Public libraries were once a haven for drowsers, but those that haven't already closed have opening hours too short and eccentric to allow for serious shut-eye. Art galleries require perambulation and don't offer comfortable chairs. The parks are full of dogshit. So it's off to the theatre or cinema if sleep is what you need. It's as easy as counting sheep.

Disquisitions from the field of aesthetics don't often acknowledge the Mogadon function of art. It's understood that, just as seeing tears wept on stage or in the movies can often make us weep in sympathy, so music and theatre which take peace and harmony as their themes may soothe the troubled brow and even risk closing the eyelids. But mimetic theory doesn't get us very far. Harold Pinter's play about sleeping sickness, A Kind of Alaska, isn't the least soporific. Chekhov explores boredom without being boring. If audiences are passing out in increasing numbers, this may tell us less about art than about the state of the nation.

In a workaholic age (and the British working week is the longest in Europe) shutting down an overactive brain is a vital task. Holidays are supposed to fulfil this role, but these come but once or twice a year, and in the meantime there's a need for rest, or at any rate catnaps. This is where the arts come in, as a branch (or mattress) of the leisure industry. In this respect, and several others, culture has taken over from the church. Generations used to be stunned and transported by the Sunday morning sermon; since churchgoing declined, they get their sleeping draught from culture instead.

Theatres, like churches, are places where, for an hour or two, the usual bodily functions are meant to be suppressed. You can't eat, drink, smoke, talk or defecate, except during the interval. You can't have sex, either: a couple who did, earlier this year, and were spotted mid-performance in a theatre balcony, found themselves in all the tabloids. To laugh or cry is permissible, and even encouraged, but only in the right places. It's remarkable how rarely people rebel or freak out in the face of these unnatural constraints. The one natural function you can perform without penalty or humiliation is sleep. Even professional theatre reviewers have been known to slumber.

It's said that Wagner started the trend of having lights dimmed for concerts, because he was fed up with people eating, chatting and not paying attention. In doing so, he helped create the conditions for a new form of inattention. It's not so much that the darkness hides all kinds of sins, but that, with its womb-like, familiar warmth, it provokes sleep as reliably as a novel on a bedside table. "Enter the dream-house, brothers and sisters," wrote C Day Lewis, "leaving/ your debts asleep, your history at the door."

I've heard it suggested that the reason people feel less inhibited about falling asleep in the theatre these days is down to television: no one feels guilty about using the box to sleep to, so why feel guilty about snoozing in the stalls? But there are differences. One locale is private, the other public. More importantly, to adopt an old distinction, one medium is low culture, the other high. With low culture - soap operas, say, or airport novels - it's acceptable to miss or skip bits; you can always replay the videotape or turn back the page, and even if you don't you may not lose out. In the theatre, or at a classical concert or poetry reading, there's that element of intense, start-to-finish performance which no recording, or return visit, can hope to capture. It's shaming, when something is live, to be dead to the world.

Writers or composers who find that their works are sending people to sleep in droves face several choices. They can take it as a silent version of a bad review, and resolve to change their tune or profession. They can decide that the dozy, imbecile public is unable to appreciate art of the highest order. Or they can shrug and remember occasions when they, too, have nodded off, sometimes in mid-composition. The best of them go on as before, writing or composing for someone awake enough throughout to notice when, say, certain motifs from the first half are recapitulated in the second.

A man recently appealed against his prison conviction because the judge had fallen asleep during the trial; the appeal was rejected, on the grounds that the judge still understood enough to reach a fair verdict. It might be argued that those who sleep through concerts likewise have some inner ear comprehendingly attuned to the music. But you can't blame musicians or actors for rejecting the homage of catatonia. The best audiences are always awake.

Neal Ascherson is away.