Grandparents have big hearts when it comes to their grandchildren, but how much is too much?

Grandparents who take care of their grandchildren at least nine hours a week have a 50 percent increased risk of heart attack, according to a new study from the Harvard Medical School.

The study, printed in the American Journal of Public Health, stated that taking care of grandchildren puts grandparents at greater risk because of stress.

“It is possible that their role caring for these children makes it difficult for them to follow basic preventive health behaviors such as exercising, eating right and getting adequate sleep,” said author Sunmin Lee of Brigham and Women’s Hospital in Boston in a press release.

Lee, who researched the theory with the Harvard School of Public Health and Harvard Medical School, said in a press release that statistics show about one in seven U.S. women have raised a grandchild for six months or more.

Lisa Schmidt, an assistant director of campus child care at NIU, has spent a lot of time working with children during the past seven years.

“I can say that, from being a teacher in the past, of course there are some days more stressful than others,” Schmidt said. “Many times, for any profession, everyone has easier days than others. But a person who is choosing to devote [his or her] professional life to children expects the challenging and stressful times and understand it is par for the course.”

Schmidt, who has a Master of Science degree in Family and Child Studies from NIU, said in her experience as a former teacher, she became accustomed to increased physical activity with the children.

“It was also in my experience that being around the children promotes a lot of activity and movement,” Schmidt said, “which for me was a healthy environment rather than being sedentary and having little opportunity to get around and move.”

Grandparents are not daily caregivers for a majority of NIU’s day care children.

“I would say that generally, the level of care a grandparent would provide for our families would be minimal during the work week,” Schmidt said. “I don’t know what happens on the weekends.”

Schmidt said the day care primarily is made up of NIU students and faculty families.

“Sometimes we will have a family or two who utilizes both the center and a grandparent for care during the week,” Schmidt said. “But I would not say that is the norm. Many times, grandparents are simply not local because of so many students coming from a variety of locations.”