Employee mental health services have become a billion-dollar industry. New hires, once they have found the restrooms and enrolled in 401(k) plans, are presented with a panoply of digital wellness solutions, mindfulness seminars, massage classes, resilience workshops, coaching sessions and sleep apps.

These programs are a point of pride for forward-thinking human resource departments, evidence that employers care about their workers. But a British researcher who analyzed survey responses from 46,336 workers at companies that offered such programs found that people who participated in them were no better off than colleagues who did not.

The study, published this month in Industrial Relations Journal, considered the outcomes of 90 different interventions and found a single notable exception: Workers who were given the opportunity to do charity or volunteer work did seem to have improved well-being.

Across the study’s large population, none of the other offerings — apps, coaching, relaxation classes, courses in time management or financial health — had any positive effect. Trainings on resilience and stress management actually appeared to have a negative effect.

“It’s a fairly controversial finding, that these very popular programs were not effective,” said William J. Fleming, the author of the study and a fellow at Oxford University’s Wellbeing Research Center.

Dr. Fleming’s analysis suggests that employers concerned about workers’ mental health would do better to focus on “core organizational practices” like schedules, pay and performance reviews.

“If employees do want access to mindfulness apps and sleep programs and well-being apps, there is not anything wrong with that,” he said. “But if you’re seriously trying to drive employees well-being, then it has to be about working practices.”

Dr. Fleming’s study is based on responses to the Britain’s Healthiest Workplace survey in 2017 and 2018 from workers at 233 organizations, with financial and insurance service workers, younger workers and women slightly overrepresented.

The data captured workers at a single point in time, rather than tracking them before and after treatment. Using thousands of matched pairs from the same workplace, it compared well-being measures from workers who participated in wellness programs with those of their colleagues who did not.

It is possible that there was selection bias, since workers who enroll in, say, a resilience training program may have lower well-being to begin with, Dr. Fleming said. To address that, he separately analyzed responses from workers with high pre-existing levels of work stress, comparing those who did and did not participate. But among this group, too, the survey answers suggested that the programs had no clear benefit.

The findings call into question practices that have become commonplace across job sectors. But researchers said they came as no surprise.

“Employers want to be seen as doing something, but they don’t want to look closely and change the way work is organized,” said Tony D. LaMontagne, a professor of work, health and well-being at Deakin University in Melbourne, Australia, who was not involved in the study.

Workplace mental health interventions may send the message that “if you do these programs and you’re still feeling stressed, it must be you,” Mr. LaMontagne said. “People who don’t have a critical view might internalize that failure: ‘So I really am a loser.’”

The corporate wellness services industry has ballooned in recent years, with thousands of vendors competing for billions of dollars in revenue. Companies invest in the interventions in hopes of saving money overall by improving worker health and productivity.

Some research supports this expectation. A 2022 study tracking 1,132 workers in the United States who used Spring Health, a platform that connects employees with mental health services like therapy and medication management, found that 69.3 percent of participants showed improvement in their depression. Participants also missed fewer days of work and reported higher productivity.

Adam Chekroud, a co-founder of Spring Health and an assistant professor of psychiatry at Yale, said Dr. Fleming’s study examined interventions that were “not highly credible” and measured well-being many months later. A blanket dismissal of workplace interventions, he said, risks “throwing the baby out with the bathwater.”

“There is recent and highly credible data that things like mental health programs do improve all those metrics that he mentions,” Dr. Chekroud said. “That’s the baby you shouldn’t be throwing out.”

There is also solid evidence that practices like mindfulness can have a positive effect. Controlled studies have consistently demonstrated lower stress and decreased anxiety and depression after mindfulness training.

The lackluster benefits that Dr. Fleming found may reflect variations in offerings, said Larissa Bartlett, a researcher at the University of Tasmania who has designed and taught mindfulness programs. “Light-touch” interventions like apps, she added, are generally less effective than one-on-one or group trainings.

Dr. Fleming’s study, she said, “misses most of these details, condensing intervention types into broad labels, engagement into yes/no, and dismissing the reports from intervention participants that they felt they benefited from the programs they did.”

A key omission, she added, is longitudinal data showing whether participants experience improvement over time. The result is a “bird’s-eye view” of the well-being of participants that “skates over changes that may occur at the individual level,” she said.

Dr. Fleming said that he was aware of the body of research supporting the treatments’ effectiveness, but that he had “never been as convinced by the very positive findings,” since the data comes from controlled trials in which the treatment is implemented very well, something that may not be the case in employer-provided programs.

Dr. David Crepaz-Keay, the head of research and applied learning at the Mental Health Foundation in the United Kingdom, who has advised the World Health Organization and Public Health England on mental health initiatives, described Dr. Fleming’s data and analysis as “certainly more robust” than “most of the research that has created the consensus that employee assistance works.”