Irvine, Calif. — Stepping away from the television, computer screen or smartphone in the aftermath of terrorist attacks or mass shootings may be beneficial to your mental health. That’s the takeaway from a new study by UC Irvine researchers showing that six or more daily hours of exposure to media coverage of the Boston Marathon bombings in the week afterward was linked to more acute stress than having been at or near the marathon. Acute stress symptoms increased with each additional hour of bombing-related media exposure via television, social media, videos, print or radio.

“We were very surprised that repeated media exposure was so strongly associated with acute stress symptoms,” said E. Alison Holman, associate professor of nursing science at UC Irvine and the study’s lead author. “We suspect that there’s something about repeated exposure to violent images or sounds that keeps traumatic events alive and can prolong the stress response in vulnerable people. There is mounting evidence that live and video images of traumatic events can trigger flashbacks and encourage fear conditioning. If repeatedly viewing traumatic images reactivates fear or threat responses in the brain and promotes rumination, there could be serious health consequences.”

The study challenges key assumptions about how people react to collective traumas, such as the idea that individuals must be directly exposed to an event to be at risk for stress-related disorders. It also raises questions about the latest edition of the Diagnostic & Statistical Manual of Mental Disorders (DSM-5), which specifically excludes media-based exposure as a potential trigger for trauma response among nonprofessionals.

“In our prior work, we found that early and repeated exposure to violent images from the terrorist attacks of Sept. 11 and the Iraq War may have led to an increase in physical and psychological ailments up to three years [later],” said Roxane Cohen Silver, professor of psychology & social behavior, medicine and public health at UC Irvine and the study’s co-author. “Our new findings contribute to the growing body of research suggesting that there is no psychological benefit to repeated exposure to graphic images of horror.”

Researchers surveyed a national sample of 4,675 adults two to four weeks after the 2013 Boston Marathon to assess acute stress responses to the bombings, the degree of direct exposure to the bombings, indirect exposure through media and prior exposure to other recent community-based traumas. People exposed to six or more hours per day of bombing-related media coverage were nine times more likely to report high acute stress than those with minimal media exposure (less than one hour daily). Symptoms of acute stress include intrusive thoughts, feeling on edge or hypervigilant, avoiding reminders of the event and feeling detached from it.

The study authors noted that while six or more hours a day of media exposure was above average, it was not deviant. “Someone can have streaming news on their computer screen while they’re working, they can have the radio on in the background, they can be checking Facebook or Twitter on and off, and watch a few hours of television at the end of the day,” Silver said. “We do not believe that people who engage in such behavior are more likely to have a pre-existing mental health condition or necessarily have a predisposition for experiencing negative psychological responses – they’re merely unaware of the impact of this media exposure.”

The researchers stress that they do not want to minimize the trauma of experiencing violent events in person but instead caution that repeated viewing of grisly images can do great emotional harm. Previous exposure to collective traumas (such as the 9/11 attacks or the Sandy Hook school shooting), a pre-existing mental health condition or a lifetime history of continual exposure to traumatic events places individuals at even greater risk of developing acute stress, according to Silver and Holman.

“When you repeatedly see images of a person with gruesome injuries after an event is over, it’s like the event continues and has its own presence in your life,” Holman said. “Prolonged media exposure can turn what was an acute experience into a chronic form of stress. People may not realize how stressful these media-based exposures are. Looking at these images over and over again is not productive and may be harmful.”

UC Irvine postdoctoral researcher Dana Garfin also contributed to the study, which was supported by the National Science Foundation and appears this week in the early online version of Proceedings of the National Academy of Sciences.

About the University of California, Irvine: Located in coastal Orange County, near a thriving employment hub in one of the nation’s safest cities, UC Irvine was founded in 1965. One of only 62 members of the Association of American Universities, it’s ranked first among U.S. universities under 50 years old by the London-based Times Higher Education. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Michael Drake since 2005, UC Irvine has more than 28,000 students and offers 192 degree programs. It’s Orange County’s second-largest employer, contributing $4.3 billion annually to the local economy.

Media access: UC Irvine maintains an online directory of faculty available as experts to the media at Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UC Irvine faculty and experts, subject to availability and university approval. For more UC Irvine news, visit Additional resources for journalists may be found at