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Part 5


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SOUND: sound of computers and whirring equipment

At Stanford Univerity's Sleep Research Center in Palo Alto, California, there's a laboratory that can monitor the sleep-and-waking patterns of up to 80 animals at one time. Physiologist Dale Edgar is studying how certain medications effect the circadian rhythms of lab rats. These drugs may help sleepy humans stay alert. Each rat is wired to a stack of electronic sensing gear.

Dale Edgar: Each one of these computers is handling about eight animals. The compouter screen is indicating whether or not the animal is drinking from its water spout or moving around inside their cage. And uh…

Smith: Looks like of these eight rats you've got one, two, three that are awake. Oops! Numer six just went to sleep. Ooop! Number one just went to sleep. These guys move fast!

Edgar: Yeah, they have rapid transitions between sleep and wakefulness. They can be asleep and have brief arousals, just like people can have brief arousals in sleep that last ten seconds, twenty seconds, sometimes a minute or so.

As all-night sleepers, humans are relatively unusual in the animal kingdom. Rats and most other creatures sleep and wake in shorter bursts, perhaps to avoid getting gobbled by predators. Dale Edgar says that scientists don't know for certain why humans sleep. The most they can prove is we sleep because we get sleepy. Edgar notes that animals with the least to fear from predators, like lions and humans, sleep the longest at a stretch. It may also be tied to how vigilant we are when we're awake.

Edgar: In order for us to function optimally and perform optimally, meaning be very competitive at certain times of the day, there's a metabolic and physiological cost. And sleep, sort of, pays back the debts ­ the energetic costs to the body and the brain as a function of these very high levels of vigilance ­ it's likely that if we didn't have these high levels of vigilance, we might not as a species have advanced as far as we have.

To help night workers fend off that natural urge to sleep, Edgar is studying medications that might temporarily bypass the circadian timekeeper, without the risk of addiction and other problems caused by conventional stimulants. A pill to temporarily boost alertness could be especially helpful to people in jobs like long-haul truck driving. They suffer the most fatal highway accidents in those sleepy hours of the early morning.


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