If it were to be reported that some famous and fateful decision had been taken when the decision-makers were drunk, the very thought would be considered scandalous. Such people (we would protest) must hold their responsibilities pretty lightly. We would feel cheated and undermined if we felt that our masters had not done all they could to keep their wits about them.

Yet there exists a vast body of evidence that another, non-chemical, agent of stupefaction can lead to inferior and erratic judgment or eccentric decision-making. It is called tiredness. Fatigue stupefies. Sleep deprivation makes monkeys of the best of us. It is within the experience of everyone reading this column that sleeplessness can be the author of perfectly idiotic behaviour and of misjudgments both large and small.

And if commonsense and personal experience were not enough, there is a weight of patient scientific observation and analysis, all backing the absolute certainty that shortage of sleep is a problem of the utmost seriousness to individuals and to society. This is no longer a guess. It has been proven. If you doubt it, look at figures for traffic accidents, broken down by time of day; look at workplace accidents; look at the Exxon Valdez disaster.

Unlike drugs, sleep deprivation offers no compensating pleasures. It can be easily, simply and cheaply remedied and the means is obvious.

Yet we all but ignore these truths. Meanwhile, we regard the mixing of work and alcohol as irresponsible. We give short shrift to those who claim they can adequately exercise their responsibilities while under the influence of alcohol because we know that, though this may be true for most of the time, sooner or later — at the wheel, at the lathe, in the boardroom or on the Floor of the House — will come a moment when every faculty is needed and cool, measured judgment vital. When we drink we forfeit that edge.

It is just the same with sleep deprivation, yet, except in a couple of specialised fields, little social or professional stigma attaches to the individual who cuts his corners in this way. Sometimes he is even admired for keeping going.

I write this in the Soutpansberg Mountains in the Limpopo region of South Africa, thousands of miles from every care and hugely refreshed by the separation.

But more than anything I am refreshed by a week of sleeping properly and for long enough at night. It helps that there is no electricity here.

The difference this sleep is making to my good humour, mental concentration, calm judgment and physical wellbeing is unmistakable. By sheer coincidence, I have with me a recent book about sleep — Counting Sheep: The Science and Pleasures of Sleep and Dreams, by Paul Martin — a persuasive and informative study, but one which tells us what we already know, if only we think honestly about it. The book, and the African sojourn, have made me think honestly about it, and I can see that the transformation of not only my mood but my competence is simply explained, and that this explanation can be applied to many other episodes in my life.

Like every little boy, I used to react with fury when my mother said “you’re just tired”, but, in common with every other little boy or girl now grown up, I should recognise that she was usually right. I am beginning to understand how much this matters.

Ten days ago both my long sight and my short sight seemed to be slipping. I was struggling for words. Names kept eluding me. I noticed during radio and television interviews that my reactions were slower. I could not find the right phrase or argument in time. Little things — stupid little things — were irritating me disproportionately. Confronting perfectly do-able lists of things to be done, I would become irrationally dismayed. I was easily deflated. I kept despairing.

Nor was this only mental. A sort of turning-point arrived when the sight of a long escalator on the Underground, broken as usual, triggered in me a sudden, tremendous rage. Climbing it, the effort of putting one foot in front of the other seemed to overwhelm me, though I knew very well that I was capable of sprinting up, two steps at a time. What was wrong with me? I thought. Am I ill?

It did strike me even then that since returning six weeks ago from the Algerian Sahara where, sleeping under the stars, we had risen with the sun every morning (and been asleep by ten every night), I had got into the habit of waking before seven but failed to continue the habit of an early bedtime. I had been sleeping five or six hours a night for more than a month. And I was losing my edge. Everyone does.

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