Edison was wrong about sleep

Thomas Edison
AP

(MoneyWatch) Thomas Edison always maintained that sleep was a criminal waste of time. So he got his own back: The invention of the light bulb was his form of crime prevention.

The problem is: He was wrong.

Talking at TEDGlobal about the neuroscience of sleep, Russell Foster made a powerful case for the critical importance of sleep. In the 1950s, most Americans slept, on average, for eight hours a day; now that number is 6.5. But it hasn't made us any more productive. It makes us grumpy, accident-prone and fat.

We get grumpy when we're sleep deprived because our brains are finely tuned to circadian rhythms and at night, it wants to sleep. If you've fed your brain caffeine all day, it will stay awake -- but still feel tired. Ordinary work will get harder, you will make more mistakes and they'll make you mad.

Thirty one percent of drivers micro-sleep, that is they nod off for a split second. This results in some 100,000 U.S. highway accidents.

When we're tired, we crave glucose, the source of energy our brains consume. So we eat all those things that we shouldn't hoping they'll give us energy when what we really need is sleep.

Tired people get very stressed and that stress incurs memory loss which, of course, provokes more stress. This in turn can start to compromise your immune system which is one reason, Foster argues, shiftworkers suffer higher rates of cancer.

Moreover, at Harvard, Charles Czeisler has shown that, when you're sleep deprived, it is very hard to catch up on lost sleep. If you habitually under-sleep, the accumulated sleep debt does as much harm as skipping the odd night. So what you need is a good sleep habit. What does that mean?

Turn off all screens at least half an hour before bed

Don't drink caffeine after lunch

Reduce light exposure 30 minutes before you go to bed -- even if this means brushing your teeth in semi-darkness.

Sleep in a cool, even cold room.

Foster argues that sleep deprivation is an early marker of mental illness. And sleep deprivation is implicated in just about every industrial accident you care to name.

It's rare to find a field of science where everyone agrees. But here they do. Get a good night's sleep. Get enough -- which is 7 to 8 hours. And make it a habit. Edison was wrong.

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    Margaret Heffernan has been CEO of five businesses in the United States and United Kingdom. A speaker and writer, her most recent book Willful Blindness was shortlisted for the Financial Times Best Business Book 2011. Visit her on www.MHeffernan.com.