Why do we worship stupid people? That's what we do as we celebrate the road warrior who jumps off of the red eye into a rental car and zooms down the highway. It's what we do when we cheer the team that kept pulling all-nighters.

Missing just one night's sleep has a noticeable impact on the brain's ability to function, as Dardo Tomasi and his colleagues at the Brookhaven National Laboratory discovered when they took 14 healthy, non-smoking right-handed men and made half of them stay awake through the night. In the morning, both rested and groggy subjects were put through a serious of tests while an fMRI scanner took pictures of their brains to find out how the rested brain differed from the one that was deprived of sleep. They found, not so surprisingly, that the sleepier the subjects, the lower their accuracy in the tests. 

But it was the details that were most interesting.

Thinking takes energy.

The scientists found that two key areas of the brain--the parietal lobe and the occipital lobe--were less active in the sleep-deprived participants.  The parietal lobe in the brain integrates information from the senses and is also involved in our knowledge of numbers and manipulation of objects. The occipital lobe takes part in visual processing. So both areas are highly engaged in processing visual information and numbers.

The thalamus, on the other hand, was very busy in the sleepy subjects. Scientists hypothesize that the thalamus attempts to compensate for the reduced activity in the parietal and occipital lobes. The thalamus sits at the center of the brain and is responsible for the regulation of consciousness, sleep, and alertness. It was, in other words, working extra hard to stay alert. When you're sleep-deprived, all the energy you might need to solve a hard problem is instead diverted to the challenge of staying awake.

Without sleep, you're making trade-offs.

What these and other studies indicate is that, yes, we can stay awake for long periods of time with little sleep, but what we lose, progressively, is the ability to think. For most of us, work isn't primarily about physical endurance, so mere wakefulness is not enough. We need to think.

Sleep deprivation starts to starve the brain. There is a reason why we tend to eat comfort food like donuts or candy when we're exhausted; our brains crave sugar. After 24 hours of sleep deprivation, there is an overall reduction of 6% in glucose reaching the brain. But the loss isn't shared equally; the parietal lobe and the prefrontal cortex lose 12% to 14% of their glucose. And those are the areas we need most for thinking: for distinguishing between ideas, social control, and to be able to tell the difference between good and bad.

What the studies show is that the cost of staying awake is very high. You can turn up when you're tired, but you can't think or be relied upon to make solid or sound decisions. This may go a long way towards explaining bad decisions. It certainly means that when someone comes into work off of the red eye, instead of applauding, you should send them home before they do any damage.

Published on: Aug 13, 2012
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