New research out of Ludwig-Maximilian-University in Germany supports the idea flexible work hours foster an employee’s health and happiness.

The research was partly funded by ThyssenKrupp Electrical Steel Europe, so researchers were able to study sleep and work schedules in a real-world factory setting. They implemented a chronotype-adjusted shift schedule — a schedule based on a worker’s sleep patterns. In other words, morning birds were never assigned to work the night shift and vice versa. Those with an intermediate chronotype served as the control.

After the new shifts were assigned, researchers measured for sleep duration and quality, social jetlag, well-being, stress, and satisfaction during their time off. And they found working based on individual sleep patterns increased their sleep during the week. Similarly, workers didn’t require as much sleep on their time off, because they were no longer trying to catch up on sleep loss. Study author Till Roenneberg called this a “double-win situation.”

While morning birds felt more satisfied with sleep during the week, also experiencing a reduction in jetlag and improved general well-being, this wasn’t the case for night owls assigned to the night shift. In fact, their improvements were so slight, researchers concluded working late into the night is hard on everyone.

Prior to this study, research has shown night shift workers are more susceptible to insomnia, diseases, such as type 2 diabetes and heart disease, as well as sleep-related accidents, injuries, even fatalities. Social jetlag in particular — a term used when the body’s internal clock doesn’t match up with an individual’s daily schedule — has been linked to unhealthy behaviors, including smoking and drinking.

Each person, as Medical Daily previously reported, has its own internal timer influenced by DNA and the surrounding environment. Work schedules aside, studies find a general lack of sleep (as little as 30 minutes every day in the week), which throws off our clock, leads to increased hunger and weight gain among several other health problems.

Researchers of the present study hope to build upon this connection in the future. They’re conducting additional experiments they’ve designed to recreate these findings in laboratory mice, which they hope will eventually influence work cultures and how people manage their time.

"We know that sleep has important implications not only on physical health but also on mood, stress, and social interactions, so that improving sleep will most probably result in many other positive side effects," Céline Vetter, lead study author, said in a press release.

Source: Vetter et al. Aligning Work and Circadian Time in Shift Workers Improves Sleep and Reduces Circadian Disruption. Current Biology, 2015.