Long hours, too much work and not enough time are common complaints among knowledge workers the term coined two decades ago by management theorist Peter Drucker to describe employees whose jobs involve interpreting information.

What happens when a roomful of knowledge workers finally hits a wall of fatigue? Productivity falls and burnout increases.

Robert B. Tucker, president of Innovation Resource of Santa Barbara, said workers spend too much of their time responding to e-mails, phone calls and voice-mail messages and not enough time coming up with innovative ideas. That’s more the fault of the employers, who have not made new hires even though corporate profits have skyrocketed.

“Workers are spending more time just tending to their daily fires,” Tucker said. “Quality thinking that produces innovative ideas comes when we have unfettered blocks of free time and no minutiae hanging over us.”

Tucker, a consultant who conducts seminars for corporations, cited the declining number of U.S. patents being awarded to companies and the lower quality of those patents as an indication that corporations have cut too close to the bone. He often quotes Jack Welch, the former General Electric Co. chief executive who said that if the rate of change inside an organization is less than the rate of change outside it, the end is in sight.

“The No. 1 barrier to innovation right now is not a lack of funding, but a lack of time,” he said.

Kathleen Thurmond, chief executive at Best Washington Uniform Supply in Long Beach, lives with her own scenario of too much work every day.

Last year, she was forced to lay off 10 employees out of a unionized workforce of 50 after workers’ compensation costs doubled. Rising health care and gasoline costs have eroded her profit margins.

“I had to outsource my accountant and fire my sales manager,” she said. “Now, I’m partly doing the accounting myself and my operations manager has taken on the role of sales director. Managers are wearing two hats and workers are picking up the slack.”

Employees who make the extra efforts and receive little recognition are candidates for fatigue and burnout,

“There’s nothing wrong with being fatigued at the end of a work day,” Tucker said. “But we need to pay more attention to what impedes our productivity and what fatigues us unnecessarily.”