The researchers followed 2300 adults for roughly 10 years. While nearly half reported sleep disruptions, those with the people problems at work had more of the sleep issues.
"Together, work and sleep take up about two-thirds of every weekday," said U-M sociologist Sarah Burgard. "But until now, very little research has focused on the connections between work and sleep for the average U.S. worker."
Previous research has shown that lack of sleep can have serious consequences ranging from traffic accidents to health problems, chronic disease and mortality. As many as 70 million Americans suffer from some kind of chronic sleep disorder.
But this is the first known U.S. study to clarify the link between work and sleep quality for all workers who have unusual work and sleep arrangements, not just rotating shift workers or medical students. Because the surveys were prospective---following the same people over time---the researchers were able to show that work conditions affected sleep patterns, not the other way around. Their analysis controlled for initial sleep quality, health, pessimism and other confounding factors.
Respondents who felt upset or bothered at work on a frequent basis, or had on-going personal conflicts with bosses or co-workers, were about 1.7 times more likely than others to develop sleep problems.
"Massive changes over the past half-century have reshaped the workplace, with major implications for sleep," Burgard said. "For many workers, psychological stress has replaced physical hazards.
Surprisingly, however, they found no evidence that long hours, or working nights or weekends---strategies often adopted by working parents to juggle childcare and jobs while minimizing the use of baby-sitters or daycare facilities---had a negative impact on reported sleep quality.