How much do you get every night? There are people in this world – and I might have been one before I bedded more comfortably into middle age – who are attracted to headlines about how much sex we all have. These days, though, as I approach my half-century, nothing excites me as much as a juicy discussion about sleep.

How to fall asleep, how to stay asleep and when we should wake up. I love it all, and the more granular detail on offer the better, so I was well stuck in last week to research that suggests that seven hours is the-optimal amount for cognitive wellbeing. The study had nearly 500,000 participants aged 38 to 73 and used brain imaging and genetic data on 40,000 of them. My own research methodology might not be so scientific – I start my diary every day with a reflection on the previous night – but my results tally. Seven hours is the sweet spot.

I find I can just about cope with life on seven hours. Much less than that and I start to fray around the edges. I’m on a short fuse and perilously close to having a tank that is empty of the ability to be patient or calm or kind or gracious. I feel wrung out, like a greying dishcloth that has been excessively squeezed. I’m less able to cope when things don’t go my way, everything feels like a potential final straw, and I fear I might go postal over the fact that I’ve been locked out of my banking app because I can’t remember the password, or that someone has moved the phone charger from its designated socket.

I am less able to tolerate the shortcomings of my fellow humans and become increasingly misanthropic and bitter. None of this is fun, and I don’t enjoy my own company when I am judgmental, so I have educated myself in sleep protocol to the extent that I have now nominated myself as the official guru for friends and family.

I can be a hard taskmaster. When I dig into the habits of those claiming to be sleep deprived, I almost always discover a cornucopia of sin and transgression. “Of course, you’re having trouble sleeping,” I exclaim, “You can’t glug whisky until midnight while channel-surfing the news and picking fights with people on Twitter and then expect to immediately and blissfully drift off. You’ve got to respect sleep!” Sometimes, if I am in the mood, I will lower my voice, put a hand on their arm, and croon, “You’ve got to respect yourself.”

Because, of course, people succumb to their bad habits due to their days being full of toil and strife. They are exhausted and depleted from putting up with the stressors of modern life, and although they know they should not look at screens while drinking wine or eating ice-cream, they can’t face the thought of being deprived of the bit of downtime they know they deserve.

I have solved this in myself through delayed gratification. I know I don’t make good decisions when I’m tired so I tell myself firmly to go to bed instead of seeking easy consolation from the biscuit tin or the internet. If I get to sleep by 11, I will wake up before six with a delicious feeling of being ahead of the game. I can then spend a whole hour – a whole hour! – doing what floats my middle-aged boat. I can write my diary, look out of the window, or step outside and enjoy the grass under my bare feet. I can play with the cats or even, if I am feeling energetic, do a few downward dogs.

So, here is how to do it. Put your phone to bed at least an hour before yourself. Read a paper book but nothing too high-octane. I’m not convinced that any of the pillows, eye masks, balms, scented candles and night oils – I’ve got the lot – are of any use, but they won’t do you any harm.

Be disciplined and don’t allow your brain to trick you into “just” sending that email you’d forgotten about, or having one last look at what is happening out there in the big wide world. You don’t want to know now. It can all wait until tomorrow. And you’ll be better placed to cope with whatever it is if you’ve had enough kip.

Sleep tight. And let me know how you get on. I’ll be so interested. Just don’t try to tell me how often you have sex. I don’t care.