Mass shootings and suicide deaths show summer peaks in U.S. study
Researchers found U.S. mass shootings and deaths by suicide both reached their highest levels in summer, pointing to possible shared risks.
By Priya Raghavan · Science Reporter
2 min read
A new U.S. study on mass shootings, suicide and summer seasonality found that both mass shooting events and deaths by suicide reached their highest levels during the summer months. The finding matters because researchers say the shared timing could point to overlapping environmental, behavioral or biological factors behind seasonal changes in violence.
The analysis covered national data from 2014 through 2021, according to SAGE Publications. Mark É. Czeisler and colleagues reported the findings in the Journal of Biological Rhythms.
The researchers said the causes of both mass shootings and suicidal behavior are complex and involve many factors. They described the seasonal pattern as an association, not proof that summer conditions directly cause either outcome.
Why do mass shootings and suicides peak in summer?
The study does not identify a single reason. The authors said shared environmental, behavioral or biological influences may help explain why mass shootings and deaths by suicide both vary by season, but more research is needed to test that possibility.
The authors connected the new findings to prior research showing seasonal variation in suicide. That body of work has found suicide deaths often peak in late spring and summer, despite the common assumption that risk is greatest in winter, when depression symptoms tend to be more severe, according to SAGE Publications.
The study adds a broader population-level comparison by looking at mass shootings alongside deaths by suicide. Researchers said the similar seasonal rhythms raise the possibility that mass shootings may share some risk pathways with suicidal behavior.
Prior research cited by the authors has found that a substantial share of people who carry out mass shootings had suicidal thoughts, previous suicide attempts or an expectation that they would die during the attack. The new study does not determine whether those individual histories explain the seasonal pattern seen in national data.
What the study does and does not show
- The researchers analyzed U.S. data from 2014 to 2021.
- They found consistent summer peaks in both mass shootings and deaths by suicide.
- They said the pattern suggests possible shared risk factors but does not prove causation.
- They called for more research on whether seasonal factors affect mass shooting risk.
The authors said future work should examine whether prevention strategies developed for suicidality can help identify people at risk of extreme violence. They also said a clearer understanding of when and why these events occur could support efforts to prevent and respond to both mass violence and suicidal behavior.
The paper is titled “Seasonality of Mass Shooting Events and Deaths by Suicide in the United States, 2014 to 2021.” SAGE Publications provided the research summary.
This story draws on original reporting from Phys.org.