Being a helpful Hank or Holly at work may come with its own hidden price, suggests a new study recently published in the Journal of Applied Psychology.

The trio of researchers, including Michigan State University’s Russell Johnson, recruited 68 employees across a wide array of workplaces, from health care to the financial sector, for their study. Once in the morning and again in the afternoon for three consecutive weeks of work, the volunteers filled out surveys that assessed how often they helped out their fellow colleagues as well as their physical and mental state. Johnson and his colleagues found that the more the workers responded to requests for help, the more they felt sluggish on the job. And it was those most inclined to care about others, otherwise known as having pro-social motivation, that felt the greatest burn from their good deeds.

“Helping coworkers can be draining for the helpers, especially for employees who help a lot,” said Johnson, an associate professor of management at the university, in a statement. “Somewhat ironically, the draining effects of helping are worse for employees who have high pro-social motivation. When these folks are asked for help, they feel a strong obligation to provide help, which can be especially taxing.”

Johnson’s team wanted to further explore the phenomenon of helping, since relatively little research has focused on the helpers themselves. The few recent studies that have been done, however, have shown a net positive effect for help-givers. A six-week study of 500 participants reported by Medical Daily earlier this April found that helping others provided greater boosts to mood and self-esteem when compared to simply treating yourself to a day off work or exercising more, and a December study published last winter found that people better handled dealing with stress the more small acts of kindness they performed.

Given that these earlier studies focused on people helping throughout the day or during their free time, though, they may not be applicable to the workplace. It might be the case that helping others can usually make us feel good, so long as it doesn’t repeatedly get in the way of our other responsibilities. And even if being charitable can put a smile on our face, that doesn’t mean that it can’t also wear us out at the same time.

As the authors note, helping is as complicated a social interaction as any other. Adding support to that astute observation, they also found that workers who got acknowledged for their help in some way felt less weight on their shoulders afterward. “Thus, help-seekers can reduce the burden they place on helpers by clearly expressing the positive impact that helping had on them,” they wrote.

Apart being from more gracious about the help we receive from our co-workers, Johnson and his colleagues advocate generally being a little more thoughtful. “This is not to say that coworkers should avoid seeking help, but that they ought to consider the magnitude and solvability of the issue before doing so and avoid continually seeking help from the same person,” they concluded.

Source: Lanaj K, Johnson R, Wang M. When Lending a Hand Depletes the Will: The Daily Costs and Benefits of Helping. Journal of Applied Psychology. 2016.