Anyone who needs an alarm clock to wake up for work is ‘out of sync’ with their body, and some companies are realizing it’s a major problem

These internal clocks are also known as “chronotypes,” or your biological predisposition to be a morning person, an evening person, or somewhere in between.

An article in The New York Times highlights a recent trend among companies across the globe: allowing employees to tweak their schedules based on when they work best.

One expert, Céline Vetter, an assistant professor at the University of Colorado at Boulder and director of the university’s circadian and sleep epidemiology lab, told The Times’ Emily Laber-Warren that as many as 80% of people have work schedules that clash with their internal clocks. These internal clocks are also known as “chronotypes,” or your biological predisposition to be a morning person, an evening person, or somewhere in between.

Scientists have been studying chronobiology for a while. But the topic has gained more widespread attention recently. For example, in his book “The Power of When,” psychologist and sleep specialist Dr. Michael Breus assigns labels to broad categories of chronotypes: dolphins, lions, bears, and wolves. According to Breus, roughly half the population is made up of bears, meaning their internal clocks track the rise and fall of the sun and they need a full eight hours of sleep a night.

You can tell if your chronotype clashes with your work schedule by asking yourself a simple question: Do you use an alarm clock to wake up? If so, Laber-Warren writes, “you’re out of sync with your own biology.”

Employees who work at companies that mandate the same, strict work hours for everyone may have it rough. But more organizations are starting to recognize the important role chronotypes play in performance, and encouraging people to figure out their own.

For example, The Times article mentions a ThyssenKrupp steel factory in Germany, which assigned shifts based on chronotypes. Researchers reported that employees got more (and better quality) sleep.

And at the Denmark offices of AbbVie, a pharmaceutical company, employees go through a nine-hour training program that helps them figure out when they should tackle tough projects, and then craft their work schedules accordingly.

This article was originally published on Business Insider.