The Science Of Sleep

Lesley Stahl Explores The Latest Findings In Sleep Research

(CBS)  By almost all measures, we are sleeping less than ever before. In 1960, a survey by the American Cancer Society asked one million Americans how much sleep they were getting a night. The median answer was eight hours. Today that number has fallen to 6.7 hours-a decrease of more than 15 percent in less than a lifetime. And from what the scientists 60 Minutes met are finding, we may be putting ourselves in a perilous situation.

Eve Van Cauter, an endocrinologist at the University of Chicago School of Medicine, studies the effect of sleep on the body. At her lab, healthy, young volunteers like Jonathan Mrock are paid to come one at a time and have virtually every system in their bodies monitored while their sleep is interfered with.

"We did a study where we restricted sleep to four hours per night for six nights," Van Cauter explains. "And we noticed that they were already in a pre-diabetic state. And so, that was a big finding."

The study's subjects were on the road to diabetes in just six days, and that’s not all - they were also hungry. Van Cauter has made a radical discovery: that lack of sleep may be contributing to the epidemic of obesity in this country through the work of a hormone called leptin that tells your brain when you’re full.

"We observed that the volunteers, they actually had a drop in leptin levels," Van Cauter explains. "Leptin was telling the brain, 'Time to eat. We need more food.'"

"Even though they’d eaten," Stahl remarks.

"But in fact they had plenty of food," Van Cauter agrees.

Several large-scale studies from all over the world have reported a link between short sleep times and obesity, as well as heart disease, high blood pressure, and stroke.

"I think it tells us that sleep deprivation is not a challenge for which biology has wired us. There's no other mammal that sleep deprives itself than the human. So it is read by our biology as a stress," Van Cauter says.

"You know, our attitude about sleep flies in the face of what you're saying. Because I think that 'You don't need as much sleep' is looked upon as something very positive," Stahl remarks.

"It's seen as a badge of honor," Van Cauter agrees. "But you know I find it amazing to see how many people are asleep within five minutes of boarding an airplane at 11 o'clock in the morning. You know, sit down and boom. It shouldn't happen. A normal adult shouldn't be falling asleep at 11 o'clock in the morning, minutes after sitting in a small, uncomfortable airplane seat. It just shows that, you know, people are exhausted."

Jonathan the volunteer hasn't been told exactly what is being tested during his stay at the lab. He just knows on day five that he's feeling kind of groggy.

He thinks it's the lights, but that's because they aren't telling him about the sounds. Unbeknownst to Jonathan, each night when he falls into what should be a restful slumber, he's actually entering an eight and a half hour battle. Jonathan's opponent is Dr. Esra Tasali, a colleague of Van Cauter, who is watching him and his brain waves from a small control room across the hall and blasting sounds through speakers on both sides of his bed.