"So, it seems to be that practice does not quite make perfect; it's practice with a night of sleep that makes perfect," Walker says. "It's this odd notion that we all think in Western civilization that we have to stay awake to get more done. And I think that's simply not true. In fact, I think if you have a good night of sleep, what you'll find is that you can get more done than if you simply stay awake."
But what if you do sleep, just not enough?
That's the focus of an NIH-funded study at the University of Pennsylvania's School of Medicine, where four paid volunteers get wired up with electrodes and spend a week and a half sequestered in a dimly lit hospital suite. They have to stay awake until 4 a.m., then are woken up at 8 a.m. for five nights in a row. Then they're given tests to measure the effects of what's called "chronic partial sleep deprivation."
"So what are you finding? What kind of effect does just four hours a night have?" Stahl asks David Dinges, the scientist in charge of the Penn study.
"Well, the first finding, and it stunned us, was there's a cumulative impairment that develops in your ability to think fast, to react quickly, to remember things. And it starts right away," Dinges says. "A single night at four hours or five hours or even six, can in most people, begin to show affects in your attention and your memory and the speed with which you think. A second night it gets worse. A third night worse. Each day adds an additional burden or deficit to your cognitive ability."
"I'm stunned by you saying one night of just four or five hours sleep, and your ability to function is already hurt," Stahl remarks.
"But remember, we're not allowing caffeine, and we're not allowing physical activity and bright light. And for most of us, probably a day or two or so, you can get by taking these, what we call the counter measures, right? But, at some point what these studies show is the impairments get so bad, that there's little to no rescue possible without getting more sleep," Dinges says.
Dinges told 60 Minutes that his subjects, like a young French woman named Hacina, get to where it seems like they're moving through molasses.
"So, overall, how do you think not having enough sleep for five nights has affected you?" Stahl asked Hacina.
"Well, my - I- I'm quiet - quieter, definitely," she replied.
"And - and - uh- what else did you ask?" Hacina asked after a long pause, seeming confused.
The testing for alertness and reaction time has real-world relevance. Virginia Tech's Transportation Institute did a study of what causes car crashes. They got 241 volunteers to agree to have their cars wired with five cameras each. Over a year's time they found that driving drowsy was the riskiest behavior of all.
"You only need two seconds to have a lapse, in driving a car at 60 miles an hour, to drift completely out lane," Dinges says. "You're off the road in four seconds. And those kinds of lapses and slowed reaction times begin to appear fairly early."
The lapses are called "micro-sleeps," and can even occur when people have their eyes open.