Water is life for humans. And while dehydration carries a lot of very serious health risks, that can ultimately become fatal in a matter of days, it turns out there are a host of other medical issues that can arise well before we could face a terminal problem. New research from the Georgia Institute of Technology has looked at athletes, who often sweat heavily during games in the heat and sun. The results of the study were startling, and should hopefully help shape not just athletic programs going forward, but also serve as a warning for anyone who finds themselves in a persistent sweaty situation.

Sweating out just two percent of your body weight in a short period was already known to have an negative impact on physical performance. But cognition, the brain’s ability to function properly, is also affected. Sweating out five pounds of water for someone weighing two hundred and fifty pounds results in a reduced ability to make good decisions or maintain consistent attention. Motor function, coordination, and even language functions are also impacted. And these negative effects get worse as the dehydration continues.

While doctors have long suspected these cognitive issues with dehydrated patients, this study offers conclusive proof of the medical issues. Hopefully, it will help guide anyone who faces the prospect of long hours in a sweaty environment to better protect themselves.