A new study has revealed that repeated exposure to violent images from the terrorist attacks of September 11 and the Iraq War can lead to an increase in physical and psychological ailments.

The study sheds light on the lingering effects of "collective traumas" such as natural disasters, mass shootings and terrorist attacks. A steady diet of graphic media images may have long-lasting mental and physical health consequences, said study author Roxane Cohen Silver.

"I would not advocate restricting nor censoring war images for the psychological well-being of the public," Silver said. "Instead, I think it's important for people to be aware that there is no psychological benefit to repeated exposure to graphic images of horror."

Over 1,300 people participated in the study and researchers measured stress nine to 14 days after 9/11 and within a few days after the start of the Iraq War. Researchers assessed the participants' mental and physical health before the 9/11 attacks and information about their media exposure and acute stress responses immediately after the attacks and after the initiation of the Iraq War. Researchers conducted follow up assessments in the three years after 9/11. The acute stress period refers to the first few weeks after the event and post-traumatic stress is any time after one month.

Almost 12 percent of the participants reported high levels of acute stress related to 9/11 and about 7 percent reported high levels of acute stress related to the Iraq War.

People who watched four or more hours of 9/11- or Iraq War-related television were more likely to experience symptoms of acute stress.

People who watched more than four hours a day of 9/11- and Iraq War-related television coverage (in the weeks after the attacks and at the start of the war) reported both acute and post-traumatic stress symptoms over time.

Those who watched more than four hours a day of 9/11-related coverage in the weeks after the attacks reported physician-diagnosed physical health ailments two to three years later.

Seeing two particular kinds of images in the early days of the Iraq War was associated with post-traumatic stress symptoms over time: soldiers engaged in battle and dead U.S. and Allied soldiers.

Researchers said the results suggest that exposure to graphic media images may be an important mechanism through which the impact of collective trauma is dispersed widely and the findings are both relevant and timely as vivid images reach larger audiences than ever before through YouTube, social media and smartphones.

"When we consider that graphic images of individuals being overcome by the 2011 tsunami in Japan were shown repeatedly, that a vigorous debate occurred last year regarding the release of the gruesome death photos of Osama bin Laden, and that vivid and disturbing images of 9/11 will likely appear on our television screens marking the anniversary of the attacks, we believe that our paper has something important to say regarding the impact of repeated exposure to graphic traumatic images," Silver said.