“With the frequency of shootings and terror attacks there is a sense of anxiety that’s building in people,” she said, “a sense of vulnerability and powerlessness.”

Dr. Smith added: “There is a heightened alarm but there can also be some desensitization that’s happening.”

The constant stream of news on social media can also be traumatic. A team of researchers at the University of Bradford in England told a British psychology conference last year that exposure to violent imagery on social media can cause symptoms that are similar to post-traumatic stress disorder, defined as a persistent emotional reaction to a traumatic event that severely impairs one’s life.

In an analysis conducted by the Bradford researchers, 189 participants were shown images and provided with stories of violent events, including the Sept. 11 attacks, school shootings and suicide bombings.

The researchers’ analysis showed that 22 percent of those who participated were significantly affected by what they saw.