A study that changed the law
Marco Túlio de Mello, professor of the Department of Psychobiology at UNIFESP and researcher at the Sleep Institute, explains how the studies conducted at the RIDC helped reduce the number of accidents on Brazilian highways
Statement of Marco Túlio de Mello to José Tadeu Arantes

“In the early 1990s, a bus company came to us to see if we could study the level of alertness of its bus drivers while driving. So, beginning in 1993, Dr. Sérgio Tufik and I began to monitor the drivers as well as the shift employees who worked on a particular schedule or always worked at night.

Our first study, published in 2000, showed that 16% of the 400 drivers interviewed reported sleeping while driving – dozing off, on average, eight times a trip. This scenario alone was already extremely serious.

But there was another item on the questionnaire that asked if they knew any co-workers who fell sleep while driving. In this case, the responses in the affirmative jumped to nearly 53%!

The findings alarmed us considerably. We brought these people into the laboratory for a new study.  Each driver was asked to go to sleep as soon as he came in from his shift. If he had traveled during the day, he slept at night. If he had traveled at night, he slept during the day. And after he awoke, we conducted an assessment of his level of wakefulness – in other words, how hard he was fighting his body to stay awake. 

We determined that the exact number was neither 16% nor 53%, but rather 48%. That is, 48% of the drivers, almost half of them, were tired when it came time for them to drive again!

We realized that this problem was due to the drivers’ work schedule. Not many people understand the biological aspects related to work schedule, so when scheduling others to work, they take into account only the quantitative aspects, in other words, the number of people on duty, without considering each employee’s individual driving status.

The idea that we have to sleep for eight hours every day is well known. It is also happens to be false.  What we do know is that people on average sleep from six hours and forty minutes to seven hours a day. And this average is decreasing over time. In other words, our society is sleeping less and less.
Another piece of data is that some people are short sleepers – they sleep fewer than six or six and a half hours and feel fine. Other people who are long-sleepers need over nine and a half hours of sleep a day.
Along with this, we have the chronotype for each. There are the early-birds who like to go to bed early and wake up early; the night-owls who like to go to bed late and get up late; and those who are indifferent, who make up nearly 70% of the population.

After evaluating nearly 10,000 people, we determined that the people on either extreme, that is, both the early-birds and the night-owls, are less suited to shift work:  they are the first to quit their jobs because they suffer so much because of this. Hiring these people to do shift work, besides incurring a higher risk for accidents, also results in losses for the companies, because employees tend to abandon the job after one or two years at most.  

From that point on, we began providing services to several companies – one of which caught our attention since it operated in nine Brazilian states. On its worst route, there were an average of 3.6 deaths for every 100,000 kilometers traveled! Just by rearranging their work schedule, determining if workers/drivers suffered from sleep disturbances, and improving their working conditions, the average fell to 0.6. This represented at least 32 deaths a year, just on this company’s routes. Money can’t buy a change like this. 

All of this data, which the RIDC helped us collect, as well as the investments that the RIDC enabled us to make, helped significantly change the company’s behavior. They helped so much that, today, I am a member of the National Traffic Council (Contran) Special Committee on Health and the Environment and, around three years ago, we were able to change the law by making assessments of sleep disturbances part of the criteria for obtaining the National Driver’s License (Types C, D and E)  – which had previously been classified generically as “professional drivers.”
The RIDC provided us a way to change the company behavior, which reduced the number of accidents, showed people how easy it is to make this change, and placed knowledge in the hands of society, especially companies. It is saving many lives on the highways and in industry.
We also began to work with train engineers and airline pilots. With regard to airline pilots, another study monitored 15,000 flight hours for a certain Brazilian company  and we surveyed the errors committed and recorded in the planes’ black boxes, ranked on a scale of one through five. We only considered the errors above three, in other words, the serious errors. We determined that these errors increased by 46% in the early morning hours. The only thing that kept the number of accidents down was the use of automatic pilot.  

The RIDC also offered us a lot of help with regard to a study on the eating habits of people who work at night and shift workers. After evaluating nearly 8,000 people, we found that people who work the night shift, or shift workers in general, gain from five to six kilos or more from the very first year they begin working the shift. And they continue to gain weight in subsequent years to the tune of 0.8 to 1.2 kilos per year. 

This means that people who work at night or shift workers are more exposed to food: they eat more because they spend more time awake and they eat foods that are higher in calories because at night, their body temperatures fall. Health recommendations call for just the opposite: eat three meals over the course of the day while it is light, and eat only light foods at night.

Because we had done all of this work, we were called before Congress to give our opinion on the new transportation law. And this new law, which limits driving time to 11 or 12 hours and establishes at least 11 hours of rest between one period of work and the next, is very good. 

We did a pilot study where drivers traveled from São Paulo to Porto Alegre as they did before, but when they made the return trip, they did so following the standards of the new law. They showed improvement in every parameter under the new law.  So all the knowledge that the RIDC has given us helped us in turn benefit Congress in drafting the new law.” 

(Photo: Juca Martins