New research reveals mass shootings and suicide deaths share summer peaks Sadie Harley Scientific Editor Andrew Zinin Chief Editor A new study has found that mass shootings and deaths by suicide in the United States share seasonal patterns, reaching their highest levels during summer months. Analyzing national data spanning 2014–2021, researchers observed consistent summertime peaks in both mass shootings and suicide deaths, suggesting that common environmental, behavioral or biological factors may contribute to seasonal fluctuations in these forms of violence. While the causes of mass shootings and suicidality are complex and multifactorial, the findings raise the possibility that mass shootings may share risk pathways with suicidal behavior.

Prior research has shown that a substantial portion of individuals who perpetrate mass shootings exhibit suicidal thoughts, prior suicide attempts or an expectation of dying during the attack. The new findings add a population-level perspective, demonstrating that mass shootings and suicides follow similar seasonal rhythms. The study builds on decades of research demonstrating seasonal variation in suicide, which typically peaks in late spring and summer despite common assumptions that risk is highest during winter months, when symptoms of depression peak in severity.

The authors propose several potential contributing factors and emphasize that the findings identify an association rather than a causal mechanism. Further research is needed to determine whether seasonal factors directly influence the risk of mass shootings and whether prevention strategies developed for suicidality extend to identifying individuals at risk for extreme acts of violence. The researchers hope that a better understanding of when and why these events occur may ultimately inform efforts to prevent and respond to mass violence and suicidal behavior.

More information Mark É. Czeisler et al, Seasonality of Mass Shooting Events and Deaths by Suicide in the United States, 2014 to 2021, Journal of Biological Rhythms (2026). DOI: 10.1177/07487304261464399 Provided by SAGE Publications