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Fatigue Standards Lag Behind Research

Posted By admin On September 15, 2010 @ 7:36 pm In | Comments Disabled

A sleep-deprived person behind the wheel or in the cockpit is just as dangerous as a drunken driver.

That’s one of the conclusions scientists have reached after years of study on the need for sleep — and what happens when people don’t get enough of it.

Scientific understanding of sleep has improved dramatically over the past 20 years with a surge of research on everything from sleep apnea and internal body clocks to the reaction times and judgments of those who are sleep-deprived. But U.S. transportation guidelines lag far behind the research.

The regulations are outdated across all sectors of transportation. Current flight-time restrictions for airline pilots haven’t significantly changed since the 1930s, although they are currently under review. Regulations governing truck and bus drivers were only recently updated, and those changes might be temporary due to legal challenges. And the U.S. Coast Guard has failed to act on at least six NTSB recommendations that date back as far as 1978 to revise hours-of-service regulations for commercial boaters.

Jim Hall, former chair of the NTSB, said it’s shocking that U.S. agencies that oversee air, rail, water and highway safety all have failed to take scientific evidence about “the limits on performance and the rest requirements for human beings and put that into the regulations.”

Tired — or impaired?

Sleep research shows startling similarities between the workplace performance of people who are fatigued and those who are intoxicated.

Someone who has been without sleep for as little as 24 hours performs at the same level as someone who has a 0.10 percent blood-alcohol content, which exceeds or matches the legal limit for driving in all 50 states, according to studies conducted in Australia, Switzerland, Austria, England and other countries.

Steven Hursh of the John Hopkins University School of Medicine, who has studied fatigue for more than 30 years, has found that tired pilots take longer to react, suffer from attention lapses and miss things. They may lose their ability to keep track of multiple things at one time, and they do a poor job of assessing risk, making decisions they would consider too dangerous if they weren’t so tired.

A tired pilot doesn’t mean the plane will crash. “Fortunately, systems are built to prevent most of the cascade of errors that would lead to accidents,” including co-pilots, relief crews, automatic systems and autopilot systems, Hursh said.

Still, pilots collapsing into a hotel bed at the end of a long day in the sky may never know how narrowly they avoided an accident, NTSB investigator Malcolm Brenner said. “The system is so forgiving that you don’t realize how close you came,” he said. “You really cut your safety margin, and most of the time you’ll land safely, but you are impaired.”

The body’s clock

Anyone who gets less than eight hours of sleep is not operating at 100 percent efficiency, said Scott Shappell, a Clemson University professor and director of the school’s Human Factors Institute.

“We’re all walking around with sleep deficits,” he said. “The joke is always: ‘My 90 percent is better than most people’s 100 percent,’” he said. “Well, that’s fine, but it’s not very funny when we have dead people.”

Shappell takes a 13-minute nap every afternoon while sitting at his desk, facing his computer. Anyone walking by might think he’s just checking his e-mail.

Rest periods as brief as 10 minutes can significantly restore the body, Shappell said, especially during a “circadian trough,” or a low period during the day when the body is most conditioned for sleep.

The body operates on an internal clock or circadian rhythm, a one-day cycle that is based on exposure to light cues. Performance dips during two parts of the day: from around 2 a.m. to 6 a.m. and again in the mid-afternoon.

It’s extremely difficult to deviate from the circadian schedule, even over time, according to NTSB fatigue expert Jana Price. That’s why people get jet lag: They’ve changed time zones, but their bodies are still following their internal clocks.

It’s also why almost nobody is truly a night owl, said Price. People who sleep during the day get only very minimal stages of deep sleep, the kind the body needs to restore itself.

“Even people who work a permanent shift-work schedule, even if you worked a midnight-to-8 a.m. schedule, it’s difficult to not be in this constant state of jet lag,” she said. “It’s almost impossible to completely train yourself to be able to function well during the night and sleep during the day.”

People who don’t get enough sleep begin building up a sleep deficit. And to satisfy that debt, they’ll begin having lapses — one- or two-second periods during which the brain starts to enter stage one sleep.

In sedentary locations, like a truck’s driver seat, cockpit or university lecture hall, a sleep-deprived person can easily fall asleep, usually after a series of micro sleeps. In a micro sleep, the head typically bobs and the person comes out of the sleep after a second or two. But before a person can even register that micro sleep, he or she might have slipped into a dozen short, quick bursts of inattention, or “micro lapses,” that the person doesn’t even realize are happening.

The matter of “micro sleeps” has never made it into regulation anywhere in the world, although it’s a frequent problem for truck drivers and others whose “job is to monitor what’s in front of you,” Price said.

Sleep disorders

More than a third of commercial truck drivers and pilots may have sleep apnea, according to the Federal Motor Carrier Safety Administration and the Federal Aviation Administration. That doesn’t necessarily mean they’ll fall asleep on the job, but it does mean they aren’t getting the kind of quality sleep they need to operate effectively.

People with sleep apnea can wake up multiple times during the night gasping for air and then have trouble falling back to sleep. This is because the throat muscles collapse, causing oxygen levels to drop dangerously low and breathing to pause, sometimes for as long as several seconds.

Few people die from sleep apnea, but like fatigue, it can seriously impair a person’s ability to function, said Janet Tatman, a sleep disorders specialist who runs a clinic with another doctor in the Phoenix area.

And like fatigue, sleep apnea’s effects have been compared to alcohol use. Someone with moderate obstructive sleep apnea performs at the same level as someone with a blood-alcohol level of 0.06 to 0.08 percent, which is legally intoxicated in most states, according to the FAA.

Sleep apnea affects between 5 percent and 10 percent of the middle-aged population and as many as 60 percent of those who are obese, according to various studies. Truck drivers and pilots are especially susceptible because they have sedentary jobs.

“A lot of research to date shows that the rate of car accidents from the sleepiness caused by sleep apnea is at least equal to the rate caused by alcohol and drunk driving,” Tatman said. “Folks who are working long hours — truckers who are driving long distances or airline employees who are traveling over 10, 12 time zones in some cases — are likely to have lots of problems with sleep and sleep quality and be at more risk for obesity.”

Sleep apnea is usually easily treated once diagnosed. A patient is fitted with a device to wear around his or her face at night to ensure enough air can pass through the airways.

Tatman said she’s had many flight attendants and pilots pay out of pocket for treatment, fearing their employers will find out about their condition if they bill their insurance companies.

New Technology

New tools are helping the transportation industry figure out how to evaluate whether someone is too tired to operate a plane, boat, truck, bus or train. One of these tools was developed by Hursh, the Johns Hopkins’ fatigue expert.

Hursh is the co-inventor of the Fatigue Avoidance Scheduling Tool, or FAST, which measures the level of potential fatigue that might result from various pilot or driver schedules.

Hursh started working on the modeling tool at the request of the Air National Guard at Andrews Air Force Base, which often flies members of Congress and other dignitaries on missions around the country. Because of the visibility and importance of those flights, the Guard needed to understand how fatiguing the flights could be and how many extra pilots might be needed.

Hursh believes models like his will become common in the next two to five years. They already are being tested in countries like Australia, England and Canada, where agencies that regulate airlines and other travel have been moving aggressively to prevent fatigue-related accidents.

The Honolulu-based company Fatigue Science, a branch of Archinoetics, is developing a tool called the ReadiBand, which measures reaction times, caffeine and light levels and monitors sleep and fatigue. It fits on the wrist and can be incorporated into a watch.

Currently, the device generates a report of activity and rest every 14 or 30 days. But the goal is to get a report at a moment’s notice, such as when a pilot checks in before a flight, said company CEO Traci Downs. The watch is being tried by about 30 airlines and several professional sports teams, Downs said. Her company expects to being offering the device to the public this fall at a cost of $300 to $400 per user per year.

Sept. 26, 2010

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