We need real sleep, not the laptop kind

The Pentagon has been funding studies of migratory birds to see if they provide lessons on how soldiers can be trained to go seven days without sleep while maintaining an ability to function at peak performance. It is also funding research into drugs, diets and hi-tech breathing masks to reduce the need for sleep.

That will not impress the coalition of scientists from Oxford, Cambridge, Manchester, Surrey and Harvard universities who have just warned that the industrialised world is storing up serious health problems by reducing the amount of sleep that we get.

The scientists' warning was strikingly moral in tone. They presented stacks of empirical evidence that a lack of sleep is increasing obesity, diabetes, strokes, heart attacks and cancer. But they also offered the distinctly unscientific admonition that modern living has made humankind "supremely arrogant" in our attitude to the natural world.

There have always been moral overtones about our attitudes to sleep. Rising early, and getting on with the tasks of the day, is usually spoken about with approval. By contrast staying up late to work and then lying in – even if the same number of hours are worked and slept – is somehow the ill-disciplined practice of the decadent libertine. Sleeping in the day is positively self-indulgent.

Six in every 10 Britons are now sleep-deprived, and yet public chatter on the matter is largely restricted to anecdotes about how Margaret Thatcher survived on four hours a night, Leonardo da Vinci took 20-minute naps every three hours so he could work round the clock, and Salvador Dali claimed he maintained his creative energy by dozing off while holding a metal spoon above a tin tray so it woke him as soon as it slipped from his fingers. Sleep is seen as the ultimate waste of time. Snooze and you lose, as the US business proverb has it.

Yet there must be a serious evolutionary point to sleep. For a Stone Age man to lose consciousness out in the wild, with nocturnal predators on the loose, is such a dangerous behaviour that it must have a benefit that significantly outweighs the risk. But what? Sleep is clearly related to the Earth's cycle of day and night. Experiments which keep animals in total darkness show that they begin to shift their sleep rhythms from a natural body clock which has evolved over billions of years.

The most recent experiments in neuroscience suggest that during sleep our brains process the events of the previous day and put out the neural dustbins. Experimenters have also shown that animals forced to eat when they would normally be resting put on weight. Research among shiftworkers – and with airline pilots crossing time zones and passing from sunlight and darkness several times a day – show disturbed sleep patterns increase fatigue.

Technology has long had a key influence here. In many ways it has been positive ever since the first candle enabled a scholar to read long into a dark winter's evening. The advent of electricity in an African village today remains a fairly unalloyed good.

But electric lighting, combined with extensive social and technological changes, have shifted our circadian rhythms with more damaging impacts. Just a few decades back, television stations stopped broadcasting just after 11pm. Pubs stopped serving then too. So, almost everyone was in bed by midnight. Today, entertainment, shopping and communications go on around the clock.

Jonathan Crary blames money. In 24/7: Late Capitalism and the Ends of Sleep he sees slumber as the final wild frontier which capitalism wants to conquer. Sleeping less means doing, making and buying more. We get an average of 90 minutes less a night than we did a few decades ago; it has gone down by 38 minutes in the past decade alone. Teenagers are among the worst offenders.

Our eerie blue-lit nocturnal screens don't just offer alternatives to sleep, they reduce its quality because the pineal gland needs darkness to make the sleep-inducing hormone melatonin. Its decline has been linked to accelerated ageing, heart attacks, cancer and immune system and neurodegenerative diseases such as Alzheimer's and Parkinson's. Skipping sleep systematically seems to be doing irreparable damage to both our bodies and brains.

Some are tempted to say that if technology is the problem it can also be the answer. The US military is also experimenting with fatigue countermeasures. Solo sailors have developed systems for short naps which aim for maximum performance on minimal sleep. They follow the research of the man they call Dr Sleep, Claudio Stampi, whose motto is: "Sleep too much and you don't win; sleep too little and you break."

Nasa is looking at ways to help astronauts to sleep longer. Then there are drugs. The NHS spends £36m a year on sleeping pills while students – one in five in one Cambridge survey – take modafinil to prevent sleepiness and increase concentration to get academic work done amid their frantic leisure activities.

Our ancestors had a different solution. Homer and Chaucer both refer to the ancient practice of a short "fyrste sleep" at dusk after which people awoke – and talked, read, prayed, had sex, brewed beer or burgled – before a second sleep till dawn, the historian Roger Ekirch reveals in his book At Day's Close. Winston Churchill did something similar. The afternoon nap is another strategy; the siesta is in decline in Europe but millions of Chinese workers still put their heads on their desks for an hour's xiuxi after lunch.

We are more than machines. Sleep mode on your laptop just means it is waiting until it can be productive again. But recreative human sleep must mean more than that. It is our only guaranteed daily change of pace. It is what plugs us into the rhythm of the natural world.