A few years ago, scientists conducted a real-world experiment at a ThyssenKrupp steel factory in Germany. They assigned the day shift to early risers and the late shift to night owls.
Soon the steel workers, many of whom had been skeptical at the outset, were getting an extra hour of sleep on work nights. By simply aligning work schedules with people’s internal clocks, the researchers had helped people get more and better rest.
“They got 16 percent more sleep, almost a full night’s length over the course of the week,” said Till Roenneberg, a chronobiologist at Ludwig-Maximilian University in Munich, who headed the study. “That is enormous.”
In recent years, U.S. educators have been paying increased attention to their students’ sleep needs, with growing debate about delaying school start times. Now a number of businesses are following suit, encouraging their employees to work when their bodies are most awake.
“It’s a huge financial burden not to sleep properly,” Roenneberg said. “The estimates go toward 1 percent of gross national product,” both in the United States and Germany.
Emerging science reveals that each of us has an optimal time to fall asleep and wake up, a personalized biological rhythm known as a “chronotype.” When you don’t sleep at the time your body wants to sleep — your biological night — you don’t sleep as well or as long, setting the stage not only for fatigue, poor work performance and errors but also health problems ranging from heart disease and obesity to anxiety and depression.
A full 80 percent of people have work schedules that clash with their internal clocks, said Céline Vetter, an assistant professor at the University of Colorado at Boulder and director of the university’s circadian and sleep epidemiology lab. “The problem is huge,” Vetter said. “If we consider your individual chronotype and your work hours, the chances are very high that there’s quite a bit of misalignment.”
Put it this way: If you rely on an alarm clock to wake up, you’re out of sync with your own biology.
Studies on workers in the call center of a mobile phone company, a packaging manufacturer and an oil transportation company show that these employees are more stressed and may experience more work-related discomfort and pain. It’s the mismatch — not the hours themselves — that matters. A 2015 Harvard Medical School study found that for night owls, working during the day increases diabetes risk.
Among the companies seeking to remedy the problem is Southwest Airlines, which allows pilots to choose between morning and evening flight schedules. The U.S. Navy recently traded an 18-hour submarine shift schedule for a 24-hour one that more closely matches sailors’ biological rhythms. And at some pharmaceutical, software and financial companies, managers expect employees to come to the office for only a few hours in the middle of the day — or to work off-site entirely.
“I think circadian rhythms will be a huge issue for human resources in the future,” said Camilla Kring, a Danish consultant who has helped employees at AbbVie, Roche, Medtronic and other companies learn to respect their natural sleep cycles. “It really makes sense to think about when people have the most energy and when they’re peaking mentally.”
Worker fatigue has played a role in many workplace accidents, most famously the Challenger space shuttle explosion and the Exxon Valdez oil spill, but no doubt countless more on the commute to and from work. The National Highway Traffic Safety Administration estimates that drowsy drivers cause 16.5 percent of fatal crashes.