Rousing the mysteries of sleep
Sun., Jan. 8, 2006
When you climb into bed tonight, you’ll be courting one of life’s great mysteries.
Everybody sleeps, and no one really knows why.
Scientists measure metabolism and read the reflected light of brain waves, yet the answer remains elusive. They’ve hypothesized about chemical buildup and synaptic connections.
“None of the theories that have been proposed have actually held up,” said Hans Van Dongen, associate research professor at Washington State University’s Sleep and Performance Research Center in Spokane.
But sleep comes to all animals. Elephants need three hours a day. Cats take 18. Porpoises sleep half-a-brain at a time so they don’t drown.
And one thing is certain: If you don’t get enough sleep, you don’t work right.
When we’re sleep-deprived, “something has gone wrong,” said Greg Belenky, director of the sleep research center. “We don’t know what it is.”
Belenky, Van Dongen and their colleagues are turning Spokane into one of the country’s leading centers of sleep research. A new sleep lab is under construction at the Riverpoint campus, which the researchers say will be the best in the country. Belenky and Van Dongen came to Spokane from top programs around the country – Belenky from the Walter Reed Army Institute of Research and Van Dongen from the University of Pennsylvania.
“When this is done, it will be the most state-of-the-art facility in the world,” said Van Dongen, as he walked around the construction work at the new lab last week. “These things don’t get built on a daily basis – or even a yearly basis.”
Once the lab is open in the coming months, it will give WSU an expanded program that includes scientists focusing on mouse studies in Pullman and those working on human studies in Spokane.
In Pullman, researcher James Krueger is working on a potential explanation for sleep that may shift from mouse to human studies in the near future – a hypothesis that sleep is the result of the combined rest states of a large number of neuron assemblies in the brain. The assemblies – known as cortical columns – help connect sensory information with action in the brain, and can go into rest states independently. When enough of them go down, theoretically, that’s when the whole body switches over to sleep.
In Spokane, Van Dongen and Belenky will be researching the effects of sleep deprivation for various workers such as shift-working police officers and medical residents. One thing they’ve found is that everyone’s resistance to sleep deprivation is so highly individualized that it’s hard to gather a homogenous sample for research.
“The ability to resist sleep deprivation is trait-like and could be genetically determined,” Van Dongen said.
That could have huge ramifications in the age of mapping the human genome. If your sleep habits have a genetic switch, scientists might – someday – learn how to flip it on and off.
The costs of sleep loss
People underestimate sleep. They think they can get by on less and catch up later, and they take lightly the effect that sleepiness has on their performance.
The more that’s discovered about sleep deprivation, the bigger a problem it seems. Studies show that performance on a variety of cognitive tasks goes down as people sleep less; people can sometimes perform well, but they tend to slow down and make more errors. In high-risk occupations, such as piloting planes or driving trucks cross-country, knowledge about the effects of even small amounts of sleep deprivation is taking on more and more importance.
“You used to have to rule sleep in as a factor” in accidents, Belenky said. “Now you have to exclude it.”
Van Dongen notes that several catastrophes in recent years included the combination of sleep deprivation and a task that requires sustained attention.
“Chernobyl, Exxon Valdez, the Challenger – all had elements of sleep deprivation in an automated atmosphere,” Van Dongen said.
Belenky calls sleep “one of the fundamental mysteries of mammalian neurobiology.” All mammals do it, as well as many other kinds of creatures, from fruit flies to jellyfish. It’s clearly a brain activity – other parts of the body can recover and recuperate with simple rest – but one that is poorly understood.
“Sleep is for and of the brain,” Belenky said. “It is the brain that sleeps and not the body, and it is for the brain’s recuperation.”
Even small disruptions in the amount of sleep, such as cutting back by 40 minutes, make a difference when cognitive skills and performance are measured. If a person skips a night of sleep to study for a test, their reaction times can triple, according to an article in Harvard magazine.
But what is sleep? Belenky said that the wide variety of analogies that are used – from a fuel tank to a computer – only illustrate the depth of what is unknown about sleep. A tank’s capacity is measurable, but sleep produces no quantifiable amount of fuel.
“What is it that sleeps?” asked Krueger. “If it’s the brain, what is it in the brain that sleeps?”
Krueger thinks he may be onto the answer, or part of it. In studies on rodents at WSU in Pullman, he has focused on cortical columns, which are tightly packed bundles of neurons found throughout the brain. The bundles can go into rest states on their own; when rats are sleeping, most of their cortical columns are, too.
It may be that sleep is a cumulative effect of the individual bundles. When enough of them go down, so do you.
Krueger hopes to replicate the research in humans, in collaboration with the Spokane lab. New, high-technology devices allow researchers to shine light into people’s brains, attached to a patch-like device on their foreheads. The light shines into the pre-frontal cortex – the part of the brain that performs higher-order tasks – and the reflections give scientists information about brain activity.
If that proves true, science will have learned a lot more about sleep. But it will not have dismantled the mystery or fully explained the power of sleep.
Sleep is so crucial and so specific that animals come out of hibernation to do it. A hibernating grizzly passes through sleep into hibernation, then “wakes up” a little bit, warms up, and sleeps for a while – before returning to hibernation.
One of the facts that bedeviled sleep researchers for years is that people are poor judges of how sleep affects them.
People suffering from sleep-deprivation often say they’re fine – even when objective tests confirm their performance has suffered.
“Some people completely underestimate their impairment,” Van Dongen said, “and some people completely overestimate their impairment.”
For one thing, people are suffering the effects of sleep deprivation, so their judgment is poor. For another, a lot of people may not realize they’re affected at all. Lots of the effects of sleep deprivation may not show up in drastic ways – they might slow down a task or muddy thinking. They extol a cost in efficiency, but not lives.
But when you’re flying a plane or serving in the Army or learning to be a doctor, poor performance can be deadly.
Belenky tells the story of an airplane crash at Guantanamo Bay in 1993. The crew was flying after at least 24 hours of sleeplessness, and the pilot became convinced that he needed to find a navigational strobe light to land – but there was no light. As the pilot flew the plane into greater and greater peril, the crew tried to warn him.
“The pilot was clearly stuck on trying to find this strobe light, at the expense of saving the aircraft,” Belenky said.
The plane crashed. No one died, but several people were badly injured. Belenky, who has kept a transcript of the cockpit conversation, said it illustrates the bizarre ways that the lack of sleep can affect the brain.
“The co-pilot asks, ‘Do you think you’re going to make this?’ ” he said. “The pilot said, ‘I’ll make it if I can find that strobe light.’ “
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