They say a happy employee is a productive employee.

But this summer, with gasoline prices inching up toward $4 per gallon, cash-strapped employees don't have much to smile about.

Here's some proof. According to Wayne Hochwarter, a professor of management at Florida State University's College of Business, Americans' work attitudes have been negatively impacted by the rising price of oil and gas.

In a FSU study of 1,000 workers across the U.S., 60% of employees say that the price of gas has significantly reduced the amount of money they have to spend on other things, while 45 percent reported the need to pay off debts more slowly or not at all. Additionally, 26 percent indicated that the cost of gas has necessitated going without basics such as heat or air conditioning, or even cutting back on food purchases, over the past few months.

What's more, Hochwarter reports that those most affected by gas prices tended to experience stress both on and off the job. Such stress include: negative views of work and the company, sluggishness, antagonistic behavior, feeling overwhelmed and sadness.

"Most of these effects can be attributed directly to distraction while at work," Hochwarter said. "Those I've talked to spent a significant amount of time worrying about their financial situation."

Hochwarter also asked whether employees felt alone in their sacrifices or if their company had to tighten its belt as well.

"Certainly, only a handful of employees noted that their company changed plans or had to go without because of the price of gas — even companies that rely heavily on fuel for their operations," he said.

That could spell trouble for small businesses. The FSU study reports that those employees most affected by gas prices who did not see the company sacrificing were less committed to getting things done while at work. Compared to those who felt that their company was doing without, those who felt alone in their sacrifice:

• Were 15 percent less committed to the company.
• Had job performance levels that were 12 percent lower.
• Were 20 percent less willing to stay late or work extra if needed.
• Were 25 percent less likely to give "maximum effort."

"The price of gas has contributed to the perceptions of many that they are simply never going to get ahead," Hochwarter said.

Not a good report for small businesses. From what Hochwarter found,  when employees feel they can't get a fair shake in the consumer marketplace, their work tends to suffer. That could make your bottom line suffer, as well.