A new study led by Malena Ivarsson from the Stress Research Institute at Stockholm University (Stockholm, Sweden) comes to the conclusion that teens who have been overexposed to violent content may become desensitized to it.
The findings are part of research ("The Effect of Violent and Nonviolent Video Games on Heart Rate Variability, Sleep, and Emotions in Adolescents With Different Violent Gaming Habits") published in the May issue of the American Psychosomatic Society's Psychosomatic Medicine: Journal of Biobehavioral Medicine.
The study divided 30 teenage boys (ages 13 - 15) into two groups; one group - called the high exposure group - played violent video games for three hours or more a day, while the other group played for an hour or less a day. Researchers had participants play Manhunt and Animaniacs for two hours each on different evenings. Following these play sessions researchers monitored the participants' heart rate and sleep habits.
They found that children in the low-exposure group who played the violent game had faster heart rates and trouble sleeping. They also reported feeling sad after playing Manhunt. Both groups had higher stress and anxiety levels after playing the violent game, according to researchers.
"The violent game seems to have elicited more stress at bedtime in both groups, and it also seems as if the violent game in general caused some kind of exhaustion," wrote Malena Ivarsson, of the Stress Research Institute at Stockholm University in Sweden, and colleagues. "However, the exhaustion didn't seem to be of the kind that normally promotes good sleep, but rather as a stressful factor that can impair sleep quality."
Researchers concluded that "the differences between the two groups' physical and mental responses suggest that frequent exposure to violent video games may have a desensitizing effect." Researchers did caution that this study did not prove "a cause-and-effect relationship," noting that "boys with certain traits" may simply be "attracted to violent games."