I wish to state from the outset that, mostly, I have no problem with people taking drugs. If you want to shovel a ton of coke up your nose before going to the Brits, that’s fine by me. Just so long as I don’t have to sit next to you.

In fact I read last week that Robbie Williams has checked into rehab because he’s getting though a handful of happy pills, 36 espressos, 60 cigarettes and 20 Red Bulls every day, and I thought “Pussy”. If you substitute the happy pills for Nurofen, that’s my daily diet as well, and I’m fine. “Fine, d’you hear.” Apart from the fainting.

However, I must say at this point that I intensely dislike all drugs that affect my ability to think properly. You see people in the garden at parties hiding behind trees claiming loudly that Jesus is out there too, and wants to eat them. And you think, “Where’s the fun in that?” And why are you now in the fridge sprinkling frozen peas onto a sherry trifle?

I once saw a group of people who’d taken some magic mushrooms, lying on the floor laughing hysterically at a tube of toothpaste. And toothpaste, so far as I can tell, has exactly the same comedic properties as Russell Brand.

Magic mushrooms, then, do not make you clever, or horny, or buzzy, all of which would be fine. They make you mental, and that’s not fine at all.

I don’t even like to take alcohol in such large quantities that no matter how carefully I marshal my thoughts into a coherent sentence they come out as a steam of incoherent gibberish.

Once, in Houston, Texas, I arrived back at my very large hotel and couldn’t remember either what room I was in or my name. So I had to spend the whole night trying my key in each of the doors, a job made doubly hard because they each appeared to have 16 or 17 locks. Fun? No, not really, unless the alternative is being eaten by a shark.

The worst drug though, by a mile, is the common or garden sleeping pill. I tried one once, on a flight from Beijing to Paris, and was so removed from anything you might call reality that to this day I have no recollection of the emergency landing we made in Sharjah. Being so out of it that you can sleep through a plane crash: that’s bloody frightening.

So last weekend, when I was offered a couple of pills for the flight back to London from South Africa, I smiled and said no. But the paramedic was very pretty and very persuasive and said they were only antihistamines rather than proper sleeping pills, so I relented and as the plane took off popped them into my mouth.

The first indication that something was wrong came 20 minutes into the Martin Scorsese film I was watching. It didn’t make any sense. Mark Wahlberg had become Leonardo DiCaprio who, in turn, looked just like Matt Damon. I didn’t know what was going on. I didn’t care. And then I fell into such a deep sleep that, legally, doctors would have been able to remove my spleen for transplant.

The next thing I knew we had landed at Heathrow and Richard Hammond — or it could have been Matt Damon — was shaking my shoulder pointing out that I had to get off. “This isn’t the Circle line,” he said. You can’t just sleep till your stop comes around again.”

I vaguely remember collecting a bag from the carousel — I think it was mine — and driving into central London to the accompaniment of many blown horns and harsh words. And I dimly recall climbing into bed thinking, “I’ll just have an hour’s kip before I go to work”.

And then it was five hours later, and I still wasn’t entirely sure how the world worked. I stared at my coffee machine for what must have been 20 minutes until the sheer complexity of the thing made me feel all weepy. So I went to work, made a mess of everything, and then went home for more sleep.

I’d love to report that the next day I felt refreshed but in fact everything was worse. I wanted to be well, but I couldn’t shake off the immense soggy blanket that had been laid on my head. Or the dead horse that had been nailed to my back.

And do you know what? I’d only taken a couple of antihistamine tablets. Whereas in Britain every year 16m full-strength sleeping pill prescriptions are issued each year. Only some of which go to Robbie Williams.

Research estimates that anything up to 1.75m people are going through life in a state that puts them somewhere in the middle of the River Styx. Which certainly explains why I meet so many bores in the course of a normal day. Technically, anyone on temazepam is not really what scientists would call “alive”.

Certainly I would like to see a law imposed whereby anyone who takes a prescription for sleeping pills is forced to hand over their driving licence. And their children for that matter.

You may write to me saying that you have trouble nodding off at night but I have no sympathy because I, too, lie in bed every night, in a fug of smoking primrose oil, with a tummy full of lettuce, counting sheep and I can’t sleep either.

But I know that getting though the next day on half an hour’s shuteye is better than trying to get though it with the reaction times, humour, and conversation of a boulder.

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