Eleven years into our relationship, I am finally prepared to admit that my partner and I have stopped sleeping together. It's not a case of the first throes of passion between a couple who met in their mid-50s sliding gently into a more companionate phase.
Nor is it a matter of him moving into the spare room because one of us snores. No, what I mean by stopping sleeping together is perhaps best expressed by turning the sentence around. Together, we stopped sleeping.
Far from our sleep problems uniting us in mutual compassion and empathy, we have entered into what I call the competitive sleep phase of our relationship. It is characterised not by boasting about how well we've slept, or sharing lurid dreams - rather by how badly we've fared in the night. When his alarm goes off at 6.20am, I ask groggily: "How was it for you?"
"Awful," he generally replies, "awake more than two hours in the middle of the night. And you?"
"Ha!" I gloat. "Thought I heard you tossing and turning. But I was awake for three hours myself..."
The winner in this bizarre competition that has come to dominate our nights together is the one who has suffered the most by virtue of sleeping the least.
Most of the couples I know in my age group have some kind of sleep issue to wage war over. Some sleep apart because the foghorn of the heavy snorer has made it the only way to prevent their marriage falling apart. According to new research from the Royal National Throat, Nose and Ear Hospital, heavy snoring rates have doubled in the last 20 years - much of it down to obesity.
Some stay put and put up with the barely bearable racket because, for them, sleeping in the same bed is sacrosanct and they believe the shattering of intimacy that separate bedrooms would create would somehow imperil their marriage more than being constantly exhausted.
For other friends, in relationships where one sleeps soundly and the other is up half the night, it's all about sleep envy. "I confess, I hate him for his ability to sleep through the night," one sleep-deprived friend told me. "Sometimes I get this desire to give him a prod or get right up close and shout 'Boo!' in his face. It's childish, I know, but it's galling to see him lying there so peacefully. He's smug about it, too. At 70, he's perky all day and professes to have the same amount of energy as when he was 30. I'm five years younger than him but, through lack of sleep, look five years older. Frankly, it doesn't seem fair."
Changes to our sleep patterns are said to be part of the normal ageing process. Having trouble falling asleep isn't the problem for either me or my partner - it's staying asleep that's hard. I used to sleep lying down but, because of digestive issues, I now prefer to be propped up by pillows so numerous, I'm practically standing. When I wake up in the night, I sometimes think I'm sitting at the breakfast table. When I can't sleep, this at least makes it easy to carrying on reading as I'm already in the right position.
My partner, meanwhile, sleeps with earplugs and an eye mask. Despite being rather deaf, he insists he can hear every murmur and bodily shift coming from my side of our very large bed.
The fact is, I've had sleeping problems ever since my son was born 30 years ago and, after those initial night feeds, I never got back into a regular pattern. My sleeping has got far worse over the years. My partner's lack of sleep is more recent. When we were first together, I marvelled at his ability to stay conked out, and without making a sound. Now he sleeps badly when he's anxious, and often when he is relaxed about every aspect of life, too.
For him, working 12-hour days as an osteopath, sleep is imperative. As a lazy freelancer, at least I can often afford to snooze late if I've been up a lot in the night. It's got to the point where, to help him sleep better, his GP has started him on an NHS CBT (cognitive behavioural therapy) course. Three sessions in, he knows more about sleep than he did before, has met some interesting insomniacs of all ages (young people are sleeping worse, too, with late-night screentime being Sleep Enemy No 1), but isn't sleeping any better than he was.
There was a time when we'd cuddle close and even have a 4am chat if we weren't sleeping. Now we ignore one another out of fear of sleep deprivation-blaming the next day.
A few nights ago, thoughtfully intending to spray a fine mist of This Works lavender sleep remedy, he tipped a whole bottle of lavender oil - another of the sleep potions in my ever-expanding armoury - on to my pillowcase, which meant having to strip the bed to avoid going to sleep dressed as a salad. Of course, this drama got me so revved up, I couldn't get to sleep at all.
I've tried being mindful, I've tried acupuncture and various tinctures and tonics. I've listened to soothing sounds, waves swishing against seashores, babbling brooks, courtesy of countless apps.
I've tried the 4-7-8 breathing trick (in case you want to give it a go, breathe in for 4, hold for 7, whoosh out slowly for 8), but I keep muddling it all up in my addled night-time state. I've even turned the white light of my Kindle so low, I'm practically reading in the dark, which I'm sure is ruining my already deteriorating eyesight.
The more I know about sleep, and I've been genning up on this admittedly fascinating subject with the help of renowned neuroscientist and sleep expert Matthew Walker's Why We Sleep: The New Science of Sleep and Dreams (Allen Lane, £9.99), the more worried I become. And the less able to sleep.
In the interests of a sharing relationship, I keep quoting bits at my partner, adding to his paranoia. Like the not-so-jolly news that if you routinely sleep less than six or seven hours a night, it will demolish your immune system, double your risk of cancer, increase your risk of Alzheimer's disease, diabetes, stroke and heart failure - exactly the sort of stuff we end up mulling over in the middle of the night.
Now, too, thanks to the wonders of science, I can also fret about telomeres, which I hadn't even heard of five years ago. These are the protective caps on the ends of our strands of DNA which point to our biological age. When we sleep badly, they shorten, and shortening telomeres link to chronic stress, depression and obesity.
Through our waking nightmare, at least my partner and I have retained a modicum of humour. As we lay to rest last night, my partner kissed me."Good night, darling," he said, before adding: "Only kidding."