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.