Miércoles 18 de Abril de 2007, Ip nº 187

Why should we have eight hours' sleep?
survey is suggesting that only a tiny minority of us are getting eight hours' sleep a night. But do we really need that much?

"Getting your eight hours" is one of those injunctions, like drinking plenty of water or not to swim in canals, that most people take at face value.

When former Prime Minister Margaret Thatcher was reported to need only five hours' sleep a night, it was taken as evidence of a near-supernaturally tough constitution.

And it's become an increasingly common sentiment that too much work and stress and missing out on our eight hours is the modern plague.

But the good news, says Prof Jim Horne, director of Loughborough University's Sleep Research Centre, is that we don't need eight hours at all.

"It's nonsense. It's like saying everybody should have size eight shoes, or be five foot eight inches.

"There is a normal distribution - the average sleep length is seven, seven and a quarter hours."

Lots of people report having more or less than the average, he said. It may all be down to genes, and what people are accustomed to.

The US National Sleep Foundation suggests seven to nine hours a night is advisable for adults, and a survey it conducted in 2002 suggested three-quarters of Americans had problems sleeping and a third were so sleepy during the day their activities were affected.

The foundation says: "In the past century, we have reduced our average time in sleep. Though our society has changed, our brains and bodies have not. Sleep deprivation is affecting us all and we are paying the price."

But Prof Horne says: "The test of insufficient sleep is whether you are sleepy in the day or if you remain alert through most of the day."

In a nutshell, if you sleep for eight hours a night go to work and find yourself lolling and drooling on the keyboard, you aren't getting enough. If you're sleeping five hours and running the country, you probably are getting enough.

And Prof Horne, the author of Sleepfaring: A journey through the science of sleep, says the idea that Victorians got lots of sleep and had a better work-life balance is a myth.

Indeed a classic demand of the 19th Century labour movement was "Eight hours labour, Eight hours recreation, Eight hours rest".

Women may need more sleep than men, Prof Horne says, due to the structure of their brains. And he says there is evidence that young children are getting too little sleep, with a detrimental effect on their behaviour.

Sleep patterns disrupted by shift work have been linked to heart disease, but this has also been linked to stress caused by unpleasant jobs, Prof Horne notes.

He stresses that sleep disorders are a 24-hour phenomenon with sufferers spending their days stressed and unable to clear their heads at night.

Leaving the bedroom and doing a jigsaw is one course of action, Prof Horne says. And the insomniac must not dwell on his problems or his condition.

As Mrs Thatcher once told the Sun: "If you brood and brood and brood... you won't go to sleep."

  12/03/2007. BBC News.