The Metro-North train derailment in New York that caused four deaths occurred when the train barreled around a sharp curve at 82 miles an hour in a 30-mile-an-hour zone. That tragic accident was followed by a shocking revelation: William Rockefeller, the train's engineer, was reportedly asleep at the controls as the train approached the curve.
How does sleep or lack of it factor in transportation accidents? And what's the solution to the problem? We spoke with Charles Czeisler, a professor of sleep medicine at Harvard Medical School.
As a noted researcher in the field of sleep deprivation and director of the Harvard Work Hours Health and Safety Group, you probably weren't surprised by the cause of this accident.
These attentional failures are common in our sleep-deprived society. In fact, there are two million people who admit to falling asleep at the wheel. One out of five motor vehicle accidents are related to sleep deprivation, which adds up to a million crashes a year and 7,500 deaths. That doesn't count train or plane crashes, of course.
In trying to dissect the anatomy of the accident, what would you want to know about William Rockefeller, the engineer of the train that went off the rails?
I'd want to know when he started his shift. The train began its journey at 5:54 a.m. The accident happened at 7:20 a.m. If you stay up all night or get up early, you are in this critical zone of vulnerability in the early morning hours, around the time of this accident, so it will be important to find out his work schedule and how many hours he had been working. You'd also want to know how much sleep he got in the last 24 or 72 hours, and how regular his work schedule was.
What other factors might be important to consider?
In the field of transportation in general, hours are quite irregular. Also there is a lot of crossing of time zones. Furthermore, such jobs often entail doing a highly overlearned task—like driving a truck or car. In fact, the engineer had been doing this job for 20 years, and it's a section of track he may have gone over multiple times.
It becomes routine—and so you are vulnerable to something called local sleep, which is where part of the brain is asleep, which happens to be the prefrontal cortex, where judgment is located. The person is attending to some extent, but they are in a kind of netherworld; part of the brain is asleep and part is awake. Please don't call it highway hypnosis or white line fever—it is not a mystical state; it has a scientific basis.
Residents and interns are another cohort vulnerable to sleep deprivation. You told the writer of a story published in our May 2010 issue that one in 20 residents admits to making a fatigue-related mistake that resulted in the death of a patient. Has the situation improved?
Resident's schedules have improved since then. We are currently working on a study to see if this has helped.
What can be done to prevent accidents related to sleep deprivation in those professions where it constitutes a risk to public health?
Employees should be screened for sleep disorders. They should be educated about sleep deprivation. There should be fatigue risk-management programs and policies that limit the number of consecutive work hours and allow for enough time off. It's also important to convey to workers that they need to use that time for sleep.
Just how much sleep does a person need?
Roughly seven or eight hours, and it is important that it not be impaired by a pathology like sleep apnea.
In layman's terms, what is the effect of staying awake for 24 hours?
It's the equivalent of being legally drunk.
What about having driver-alert devices on trains?
Currently most trains use outdated technology. There seems to be little effort to employ new technology to prevent these fatigue-related accidents. The Federal Railroad Administration did a five-year study of main-track train collisions; 29 percent were possibly fatigue-related.
How do other countries handle this issue?
In the European Union there is no job where you can be required to work more than 13 consecutive hours a day, and you must be provided 11 hours off per 24 hours.
What kind of research is being done on the federal level?
There is no real program in the Department of Transportation for research on fatigue. Considering it is responsible for such a high percentage of incidents on highways and in all modes of transportation, it's an area that needs attention. We need to have a national conversation about the hazards associated with sleep deprivation. It is also detrimental to health and associated with metabolic disorders and cardiovascular events. It impairs immune system response and leads to depression. It is a physical and mental public safety hazard.