AAAS/SciLine

Amruta Nori-Sarma of the Environmental Health Department at Boston University School of Public Health.

The past seven years have been the warmest on record, and climate change promises more extreme weather events to come.

A study of three-and-a-half million emergency department visits across almost 2,800 counties shows extreme heat significantly raises rates of ED visits for mental-health-related concerns.

"One of the things that we could hypothesize would be disrupted sleep periods that are happening because people are experiencing high temperatures," said lead author Amruta Nori-Sarma of the Boston University School of Public Health.

The pattern holds true across all mental health conditions, which suggests heat can exacerbate underlying causes.

“Because we see these similar rates across all of these different outcomes that are associated with mental health, we might imagine that people are experiencing stress on top of whatever other characteristics they're facing that are leading to mental illness,” said Nori-Sarma.

The research appears in the journal JAMA Psychiatry.