Jenni Murray

I discussed it in public for the first time around 10 years ago. There had been a news report about the Queen and the Duke of Edinburgh, who had been travelling on the royal train. The newsreader had said, "Prince Philip was woken by a single shot. The Queen... several carriages away..." And the younger members of the Woman's Hour production team seemed to find it rather shocking, but understandable for an elderly couple.

It was not, I told them, a question of age. I explained that we had been doing it for some 20 years and we were far from old. Sure enough, jaws dropped, as happens every time I reveal that my partner and I have had our own rooms for the majority of our lives together. I'm asked how is it we seem so happy together. I assure them we are. They want to know why I'm not ashamed of it. I joke that it's pretty cool to be able to tell your mother, honestly, that you don't sleep with your boyfriend. Then they say they would be hurt and I admit that, at first, so was I.

It came from him, after eight years and two children together. He chose his words with studied care. Would I mind very much if he moved into the spare room?

"Would I mind?" I shrieked! Was he mad? Did he not love me any more? Did he not fancy me any more? I ordered him to pack his bags and get out.

Happily, he ignored me and explained that none of my accusations had the slightest foundation. It was just that number two son, now able to throw himself out of his cot and crawl across the landing and into our bed, had developed the habit of scratching his father's back with his toenails in the certain knowledge that Dad would get up and sleep somewhere else, thus securing my undivided attention for the entire night.

It was a perfectly reasonable request, but for some weeks I agonised that, despite his protestations, this would signal the end. We both come from families where Mum and Dad sharing a bed was a given. We had followed their lead, fitting together like spoons and finding each other's presence comforting, warm and sensual. We'd giggled together at the bumps that came between us through two pregnancies and snuggled with our newborn infants through the long nights of breastfeeding. How, I wondered, could he walk away from such intimacy?

As I learned to stretch out and luxuriate in the expanse that was all mine (small children permitting), I began to realise that the marital bed had not been all it was cracked up to be. Now the duvet stayed exactly where I had put it. I could get up to go to the loo without fumbling in the dark for fear of waking him. There was no pinching each other's noses in a vain attempt to put a stop to snoring and, best of all, I could read for as long as I liked in a blaze of bright light without any complaint.

I have always read before going to sleep – as a child, snuggling under the covers with a torch after lights out. I had been reduced to similar underhand tactics with David. Even a specially purchased, tiny light that hooked over the cover of the book was too much for him. He would complain he couldn't sleep, and when I hid it over the edge of the bed, ruining my eyesight in the gloom, he would whine, "But I can hear you turning the pages!"

I began to ask myself why we enter a lifetime's commitment to another person and willingly surrender one of the most precious things we've enjoyed – a room of one's own, decorated in one's own taste, tidy or untidy as suits you. When did it become a romantic imperative to sacrifice the right to private, exclusive space for the notion of togetherness?

There is little historical record to answer the question. Pepys in his diary of 1660 indicates that a civil servant of high standing would expect to share a room with his wife. The size of the house would have been the most important factor. In a poor, working-class family, there would have been 10 to the bed, if necessary. In an aristocratic family, the master would have his chamber and the young wife her own, awaiting the footfall of her lord.

Marie Stopes, writing in 1918, extols the virtues of the marriage bed in her book Married Love, but recommends a single bed "in a nearby dressing room for when either of the partners desires solitude". Nevertheless, the idea that happiness is a big double bed exerts a powerful hold. One woman told me she would love a room of her own. At the moment, she feels her only space is the kitchen. But when she mentioned it, her husband sulked for days because he thought she didn't love him.

Another friend told me of the agony of her husband's insomnia – what she described as "the aural symphony of the restless man". He, too, had sulked for England when she suggested she had a right to a decent night's sleep and he might move to the spare room. He refused. As Katharine Whitehorn once wrote, "For the average woman, the only space that belongs to her is her half of the wardrobe."

Of my own arrangement, I can say only this: for 22 of our 31 years together, we have had separate beds. There is no shortage of intimacy – physical or otherwise – but not at night-time: that's for peace and tranquillity.

Pepys revealed something else in his diary. He said that Mrs Pepys liked to have the dog in the bedroom. Mr Pepys thought it should sleep in the cellar. "So to bed, he said, where we did quarrel all night." And that might have been the same for my partner and me, when my new hot-water bottle came to live with us. He's called Butch. He's a chihuahua. He likes nothing better than snuggling under the duvet with me. He knows it's not allowed, should there be bedroom activity in the afternoon. But at night I'm all his. In other circumstances we, too, might have quarrelled all night. As it is, everybody's happy, till, I hope, death do us part.

• My Boy Butch, by Jenni Murray, is published by HarperCollins at £12.99.

Lionel Shriver

It is the small window of your day when you enjoy perfect focus. You've already flossed and brushed, so no temptation beckons, like chocolate or port. Once you rest into plumped pillows with your eyes closed, the sheets lose their bite and your hands grow warm enough to reach for the novel on the bedside table. Miraculously, it is a good book, one to which you look forward.

When he walks in, you are already absorbed, and he's careful not to interrupt you. He undresses without ceremony. After all these years, you still glance slyly from the page to appreciate the fine sculptural rhythm of his figure. What a handsome man. How well he has aged. How clever you were to spot that vintage bottle, which would only improve in the cellar.

He dives under the duvet and screams, followed by a hyperventilating huff: "UH-huh-UH-huh-UH-huh!" You roll your eyes. In all seasons but summer, he does this every night. He blames you for the cold: you're the one who insists on no central heating in the bedroom. The screech is a little joke, presumably tireless. You pretend to find the theatrics tedious. But you would be disappointed if he didn't scream.

Of course, in a few minutes your lair is toasty. The contrast of the sharp air in your lungs is refreshing. Far from finding the bedclothes too bracing, you both sink into a level of contentment that feels dangerous. You never want to leave the bed. You could spend the rest of your life in bed. Any undertaking that requires leaving the bed now seems horrifying.

He burrows into the Economist. He says, "You'd like this article on the war between the public and private sector." You say, "You'd like this Francine Prose, too." You each apply exacting standards – you pass on only one novel in five – and will heed these recommendations. One of the best things about your marriage: you trust one another's tastes. This reprieves you both from reading all manner of rubbish.

The concentration is bliss. Though no one speaks, reading side by side is inexplicably richer than reading by yourself.

You're now reading with one eye closed. That is the sign. You switch off the light, and turn on your side. Soon his light goes off as well. The wrapping begins. One knee nestles behind yours. One fine, high arch rests on the round of your calf. He clasps your hand. His cheek lies on your shoulder. The fit is exact, much like your reading tastes. This, too, is the reason you married, much more so than what you do on more active nights. You are each other's geometric destiny. You feel at once protected and protecting. It is like holding yourself.

The descent is soft, graceful and swift. But you're not disappearing; rather, going somewhere else. Somewhere compelling, playful, exotic – just like fiction, a place to experiment with peril, angst, comedy and disaster in a state of perfect safety. You go far away and stay put. Yet the distance is never so great that you lose that small awareness of your fellow traveller on the next pillow.

Unfortunately, you are over 50. He senses it before you do, having become attuned to a sudden glow of your skin, and regretfully disengages. He calls them "fits": conflagrations that have ignited between five and 15 times a night for four solid years. You have finally trained yourself not to get furious. Methodically, you turn over a neat triangle of duvet, like making the first fold of a paper aeroplane, rinsing your body with the chill air. (And he wonders why you turn off the central heating.) A hand between your knees keeps damp thighs from touching. You are a superhero, a human torch. They say it lasts four minutes. When you get cold again, you fold the triangle back. You marvel at the patience of women. So few of your friends complain.

Alas, all this readjustment has moved him on to his back. He snores, as he always does in this position. You push carefully on his shoulder, whispering that he needs to get off his back. You have learned to use your sweetest, kindest of voices – since, like most men, when he thinks he's been caught doing something wrong, he gets mad at you. You have emphasised in waking hours that there is no reason to feel embarrassed by the passage of air through the sinus. He claims that you snore, too. You don't believe him.

Adventures. Grand visions – mountain ranges and seas. He plays a part in several escapades, now double company: inside your head and out. "The saxophone is on the blue side of the pane!" he announces loudly. It makes no sense. He talks in his sleep. He claims that you do, too. You don't believe him.

The time does not simply vanish. It passes – sumptuous, languorous and thick. Sleep is the very opposite of death. Your experience of being and only being is at its most intense.

The alarm rings on his table. It keeps ringing. Because of his profession, his hearing is poor. You don't know why he bothers to set that thing when the only person it wakes is you. You kick his leg. This is his real alarm clock. Finally he rouses enough to shut off the beeping, and goes right back to sleep.

You wrap again, in reverse: you pressed against his back. It is glorious, and you hate the waking world. You never want to do anything again. This is the point of existence. Everything else is extra and stupid. This is the best part of the day, and it will be all downhill from here.

Finally you kiss the sweet hollow beneath his jaw. "Hey," you say. "I'm going down to make coffee. So get up. You have to buy me my newspaper."

Your sole motivation for crawling from the sheets is the promise of this same exquisite ritual in 16 hours. You can't wait.

• Lionel Shriver's most recent novel, So Much For That (HarperCollins), is now out in paperback.