A recent University of Michigan study has investigated the role that work plays on people’s sleep, a relationship that, until now, has been overshadowed by the reverse association of sleep problems affecting work.

Researchers analyzed two nationally representative surveys of 2,300 US adults that monitored the same workers for up to ten years. Over this time, nearly 50% of participants reported trouble sleeping.

Because the study followed the same people over a large span of time, researchers were able to prove that work conditions affected sleep patterns, and not the other way around. Subjects 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,” says Sarah Burgard, sociologist at the University of Michigan. “For many workers, psychological stress has replaced physical hazards. Physical strain at work tends to create physical fatigue and leads to restorative sleep, but psychological strain has the opposite effect, making it more difficult for people to sleep.”

Now taken as common knowledge, previous studies have proven that a lack of sleep can have serious consequences on health. However, this study is the first to clarify the link between work and sleep quality for all workers, not just the commonly investigated shift workers are characterized by their erratic sleep/work patterns.

The findings were presented at the annual meeting of the Population Association of America on April 17.