New research has revealed that many employees experience such high levels of stress at the hands of rookie managers who are unprepared for the role, that it’s keeping them up at night.

In fact, about a fifth of U.S. workers said they had trouble sleeping when working under a newly promoted manager, according to a study from Oji Life Lab and Harris Poll. 

What’s more, 40% of the 2,000 U.S. workers surveyed said that working under a first-time boss has been the source of “stress or anxiety about going to work,” as well as dwindling motivation—and it’s causing a third to reconsider working at their companies entirely. 

Women feel the brunt of first-time managers more

For women, first-time managers had an even greater negative impact: While just over a third of male employees reported feeling stress or anxiety when working for a fresh-faced boss, this rose to almost half of female staffers.

Women workers were also more likely to have negative feelings about their career path and poor quality sleep at the hands of a new boss. 

Perhaps most alarming for corporate leaders, new bosses could be inadvertently sabotaging companies’ efforts to close the gender gap and pull women through the ranks: 40% of the women surveyed cited new managers as fueling their desire to quit, compared to 29% of men.

What’s more, this experience worsens with age: Women over 55 were the most likely to rate new managers as weak at “handling difficult situations” and “providing feedback.”

Linda Hill, a Harvard University professor of business administration who has studied management for over four decades, told Bloomberg that this might be because “most new managers believe that to treat people fairly is to treat them the same way.” But different groups have specific needs and concerns—like childbearing and menopause—that require targeted treatment from managers.

New managers are uniformly pretty bad at it for the first year 

First-time managers are far worse at making decisions, reducing conflict, running productive meetings, and providing quality feedback than seasoned leaders, making their workers’ jobs unnecessarily harder. according to the survey.

The researchers pointed to “inadequate training” as the reason behind this skills gap.

Ultimately, then, the blame for workers’ anxiety-filled sleepless nights and subsequent exodus lies with employers who promote people into managerial positions without prior training.

“We wouldn’t ask a surgeon or a pilot to learn on the job but that’s what we do every time we promote someone to be a first-time manager with no training,” Matt Kursh, cofounder and CEO of Oji Life Lab, said in the study’s release. “It’s no surprise that these freshly-minted managers have anxious teams that want to quit; the managers are unskilled at decision-making, cultivating good communications, coaching people to success, and a range of other universal leadership skills.” 

But the good news is that all of these skills can be mastered—in time. “Even if you’re going to turn out to be a good manager, you’re still going to have a bad first year,” Hill said.