Mark Zuckerberg wants you to think working in the metaverse is the next big thing, but the nascent virtual worlds still have a few kinks to work out.

The Meta CEO is one of many tech executives who believe that our workplaces are set to be revolutionized by the metaverse—an experimental amalgam of immersive and interactive digital worlds accessed through virtual reality headsets.

But while working in the metaverse with personalized avatars, holographic presentations, and even virtual bowling nights may sound fun, the reality of digital office life might be much less enjoyable, and even come with some significant health drawbacks.

Working in the metaverse for an extended period of time can lead to higher anxiety, a perception of higher workloads, and even adverse physical effects for some employees, tech outlet New Scientist reported, citing a recent study published on preprint database arXiv on June 8. The experiment has not yet been peer-reviewed.

The study, conducted by researchers from a number of European institutions including Coburg University in Germany and Cambridge University in the U.K., compared the experiences of 16 university staff or researcher participants who spent a 35-hour workweek in normal, physical office spaces, and another week doing the same work in virtual reality.

The researchers wrote that working in VR for a week resulted in “significantly worse ratings across most measures” for participants, particularly in terms of health effects and productivity.

Employees’ anxiety over their job also increased by 19% when working in the metaverse, while their perception of their workload grew by 35% relative to the week spent in a physical office, despite researchers ensuring that workloads in the virtual and physical workweeks were similar. Additionally, workers reported their “frustration” with being unable to complete work in a timely or efficient manner increased by 42% while in VR, while self-reported productivity fell by 16%.

The adverse effects working in the metaverse had on employees were not limited to mental health, as several experienced severe physical problems too.

All participants reported more frequent or intense instances of eye strain, visual fatigue, and nausea. One participant reported a headache that lasted three hours after 45 minutes of intense work, and two employees even dropped out of the study on the first day due to feeling extreme nausea, anxiety, and severe migraines, as well as discomfort with the VR headset.

The researchers conceded that they had not acquired the best or most comfortable VR technology for the participants to use, but this had been by design. The study aimed to verify how employees with more modest budgets would fare in a metaverse office space, not only those who can shell out up to $3,000 for a high-range VR apparatus.

As many as 71% of executives say the metaverse will have a positive impact on their organization, according to an April survey of global executives conducted by financial services company Accenture, with 42% saying it will be “transformational.”

But with severe health effects still being observed in users, it may be a while before metaverse applications in the office take hold.

Cybersickness—an affliction akin to motion sickness common in virtual reality environments—has been known to researchers for years, often accompanied by symptoms of nausea, dizziness, and headaches. But with Zuckerberg and other tech CEOs promising the forthcoming ubiquity of the metaverse, virtual reality’s health symptoms are becoming more relevant.

A prolonged time spent in virtual reality spaces could aggravate symptoms linked to digital eyestrain, including blurry vision, headaches, and dry eyes. Some users who have worn VR headsets for hours at a time every day have even complained that the technology led to permanent eye damage, although research into the long-term consequences of VR use is still scarce.

The researchers in the recent study pointed out that many of the participants may not have had prior exposure to the technology, and getting accustomed to it may have contributed to their frustration.

“There was some indication that participants gradually overcame negative first impressions and initial discomfort,” the authors wrote, suggesting that a hybrid working schedule split between the metaverse and the real world may be the best option to conserve productivity if employees are getting used to working in virtual reality.