Erina MacGeorge of Purdue University, in West Lafayette, Ind., studied how college students coped after the Sept. 11, 2001, attacks. She urged people to listen to students' fears.

"Even though there is geographic distance between other students and this university, there is still a great possibility for students to experience stress because they can relate to the campus environment," MacGeorge said in a statement.

"The intense media coverage makes such an event seem even closer to home, and even college students who are hundreds or thousands of miles away may be connected to students at Northern Illinois University through communication technologies such as an instant messenger or Facebook," said MacGeorge.

Many people can cope with bad situations by talking about it with their friends, she said.

However, symptoms of extreme distress -- such as being unusually upset, not sleeping well, or having problems concentrating -- may indicate a need for professional counseling, MacGeorge said.

"It is important for the listener to not minimize the situation," she said. "They should be careful when trying to distract the person from the problem. It can be seen as trivializing the person's fears."