These should be good times for American workers. The U.S. is nearly ten years into one of the longest economic expansions in history. Unemployment is the lowest it’s been in almost half a century. Wages are beginning to rise, and employees have more job choices than they’ve had in years.

But the mood of employees is far from happy. In fact, the mental well-being of employees hit a five-year low in 2018. That’s what we found when we did a retrospective analysis of data from our digital mental health and well-being platform, Happify, examining almost half a million first-time users of the platform between December 2014 and January 2018 who identified themselves as being employed. All changes in prevalence of depressive symptoms were calculated as relative percentage changes.

Our data showed that over that five-year period, the prevalence of symptoms of depression among employed Happify users increased 18%. Particularly alarming is the proportion of young adults whose mental well-being deteriorated over that time-frame. The prevalence of depressive symptoms spiked 39% among Generation Z employees (ages 18-24). While Millennials (ages 25-34) fared a bit better, they also experienced a large jump in their rate of symptoms of depression—up 24% in those five years. Those are extremely high increases, and while there many reasons we might see such dramatic increases among our users— perhaps there has been a shift in who chooses to sign up for our service —it jibes with what other studies of young people have found.

For example, a 2018 survey from the American College Health Association found that more than six in ten undergraduates experienced overwhelming anxiety in the prior year and four in ten had felt so depressed that they had difficulty functioning. According to the National Institute of Mental Health, more than one in four young adults (18-25) have some degree of mental illness, the highest prevalence among all age groups.

This leads me to suspect that the rise in mental health conditions among younger people heralds a new normal and could very well become an issue for companies as more Generation Zers enter the workforce. Declining mental health in the workforce means higher costs and productivity losses for employers. Depression costs businesses about $210 billion dollars annually and 32 days of lost productivity each year for every employee suffering from depression. What should be sounding alarms for employers is that their younger employees, those who will have the greatest impact on the workplace for years to come, are in the worst mental state. Millennials already make up the largest segment of workers and Generation Z currently comprises about 20% of the workforce, with more entering every year.

It’s true that young adulthood has always been a turbulent and challenging life stage. People in their twenties are typically entering the workforce for the first time, adjusting to what it means to be a “grown-up,” and trying to figure out who they are and what they want to do with their lives. But the high levels of mental health disorders seen in today’s young adults is different from the past, with evidence showing that more Generation Zers and Millennials are suffering from depression and anxiety than previous generations.

The bigger question is: why? And this is a much tougher question to answer.

Both Millennials and Generation Zers have also felt the brunt of globalization and growing economic competition that has put increased pressure on them to excel to succeed, starting even before high school or college. Technology has created round-the-clock connectedness and demands, making it difficult to get away from school bullies—and later, from work—and have true down-time.

Many Millennials came of working age at the height of the economic recession when job prospects were slim to none. Even though the employment landscape has turned around since then, experiencing those work-related anxieties at the beginning of a career could have lasting effects. There is no doubt that the Great Recession has set them back financially. Millennials are the first generation to earn less than their parents did, and many have little hope of ever catching up.

This dark cloud, however, does have a silver lining. Younger adults are far more open about their mental health problems and more willing to seek out different types of treatment, including both traditional therapy and complementary approaches, like telehealth and other digital tools. For employers, this means greater options for the mental health services they can provide their employees, as well as treatments that can be more accessible, scalable, and affordable.

In the past decade, employers have embraced a range of wellness programs that help employees stay physically healthy. It will be imperative for companies to offer comprehensive mental health services to address the growing mental health needs of their workforce. If they don’t, not only will their employees suffer, but their business could as well.

Ran Zilca is Chief Data Science Officer at Happify Health.