Mondays can start off poorly, especially if you've got a bad boss. Or a mean boss. Or an incompetent boss.

Psychologist Robert Hogan, an expert on personality assessments, has seen them all.

"Every employed adult reports some significant time working for an 'intolerable boss' and those (employees) that try to defend themselves are gone," Hogan, of Amelia Island, Fla., told a session this weekend at the annual conference. The meeting, which drew more than 10,900 psychology professionals, wrapped up Sunday.

"Seventy-five percent of working adults say the worst aspect of their job - the most stressful aspect of their job - is their immediate boss," Hogan said. "Bad managers create enormous and are a major source of misery for many people."

Hogan says a "major cause of stress in modern life is bad management," because stress negatively affects the immune system and health.

His firm, based in Tulsa, Okla., helps large companies determine which individuals to hire for top-level management positions or to coach existing managers.

Other leadership consultants across the country agree that the impact of immediate supervisors is more far-reaching than many would believe.

" 'Employee engagement' has become a buzzword in corporate America," said Gordy Curphy, a leadership consultant in St. Paul, Minn., who did not attend the conference. "Twenty years ago, was (a) big deal. That has morphed into employee engagement. Research shows that the higher percentage of people engaged in the workforce, the better business results companies get. There is a clear link between employee engagement and financial results.

"There's also a clear link between your immediate boss and the level of . We know mean bosses and incompetent bosses are some of the biggest reasons why employees become disengaged," Curphy said.

Hogan's presentation included a mix of research, including a 2010 survey conducted by the Economist Intelligence Unit, part of the international company the Economist Group. It found that 84 percent of respondents believe alienated employees are one of the biggest threats to their business. He also cited a 1999 job-stress report from the National Institute for Occupational Safety and Health, which included data showing that one-quarter of employees view their jobs as the major stressor in their lives and that problems at work are more strongly associated with health complaints than any other life stressor, including financial or family problems.

Business psychology professor Tomas Chamorro-Premuzic of University College in London, a visiting professor at New York University, agrees that those who reach the top tier of management don't always mesh with employees.

"The factors that help these people get promoted contribute to ruthless top managers, who are ambitious, selfish, very tough and harm staff morale," he said.

But Chamorro-Premuzic, who is also a consultant, added that it's not always the manager's fault. He says three potential sources of trouble are the manager, the employee and the fit between the employee and the job.

"People choose jobs that are not ideal for them," he said. "The realities of the job market today is to have a job or take an offer without thinking whether it's the right job for them. That leads to dissatisfaction and complaints. They might blame their bosses or managers."

The consultants agree that in this economic climate, trying to find another job isn't the best solution.

Rob Kaiser, a partner with a leadership firm in Greensboro, N.C., said it's best to "hunker down and hope the bad boss gets in trouble and removed or kicked upstairs and you get somebody else or you get that transfer."