Sunday MBA provides ideas on running better businesses and succeeding in the modern workplace, this week from Harvard Business Review and Emma Seppala, science director of Stanford University’s Center for Compassion and Altruism Research and Education and author of “The Happiness Track.’’

There’s an age-old question out there: Is it better to be a “nice’’ leader to get your staff to like you? Or to be tough as nails to inspire respect and hard work? Most people still assume the latter is best.

The traditional paradigm just seems safer: Be firm and a little distant from your employees. The people who work for you should respect you but not feel so familiar with you that they might forget who’s in charge. A little dog-eat-dog, tough-it-out, sink-or-swim culture seems to yield time-tested results and keep people hungry and on their toes. After all, if you’re a leader who seems to care a little too much about your employees, won’t that make you look “soft’’? Won’t employees work less hard?

New developments in organizational research are providing some surprising answers to these questions.

“Tough’’ managers often mistakenly think that putting pressure on employees will increase performance. What it does increase is stress — and research has shown that high levels of stress carry a number of costs to employers and employees alike.

Stress brings high health care and turnover costs. In a study of employees from various organizations, health care expenditures for employees with high levels of stress were 46 percent greater than at similar organizations without high levels of stress. Then there’s the effect on turnover. Research shows that workplace stress can lead them to look for a new job, decline a promotion, or leave a job.

Is it any better with “nice’’ managers? Do employees fare better? Do kind bosses get ahead?

Contrary to what many believe, Adam Grant’s data shows that nice people can finish first, as long as they use the right strategies that prevent others from taking advantage. Harvard Business School’s Amy Cuddy and her research partners have also shown that leaders who project warmth — even before establishing their competence — are more effective than those who lead with their toughness and skill.

Why? One reason is trust. Employees feel greater trust with someone who is kind.

One interesting study shows that when leaders are fair to ­members of their team, the team members are more productive, both individually and as a team. Research by Jonathan Haidt at New York University Stern School of Business shows that when ­leaders are self-sacrificing, their employees become moved and ­inspired.

Such a culture can help mitigate stress. As brain-imaging studies show, when our social relationships with others feel safe, our brain’s stress response is attenuated. There’s also a physical effect. Positive social interactions at work have been shown to boost employee health — for example, by lowering heart rate and blood pressure, and by strengthening the immune system. In fact, a study out of the Karolinska Institutet, a Swedish medical university, found that a leader’s qualities were associated with incidence of heart disease in their employees. A good boss might literally be good for the heart.

In fact, employees prefer happiness to high pay. Happier employees make not only for a more ­congenial workplace but also for improved collegiality and customer service.

Taken together, this body of ­research shows that creating a leadership model of trust and ­mutual cooperation might help create a culture that is happier, in which employees help each other, and (as a consequence) become more productive in the long run. No wonder their nice bosses get promoted.

What is clear is we’re going to have to start valuing kindness at work more. One depressing study out of Notre Dame University ­suggests that for men, the more agreeable they are, the lower their pay rate. Because agreeableness does not affect women’s salary, the researchers theorize that when we don’t conform to gender norms, we’re punished.

The answer is not for men to be cruel but for us all to help change the norms. With a little skill, there are ways to be agreeable while not being a pushover or a softy. And then maybe we’ll all be a little bit happier at work.

Reprinted with permission of Harvard Business Review.