Ever wondered why you get brain fog when you’re hot, dehydrated or both?

Scientists at Georgia Tech have used brain imaging technology to show the effects of heat and dehydration on cognitive function. And it could have significant impacts on those working under these conditions.

In the study, subjects performed a repetitive task for 20 minutes under three separate sets of conditions:

  • after relaxing and staying hydrated
  • after extended heat, exertion, and sweating, and drinking water during exercise
  • after heat, exertion, and sweat but without drinking water

There was some decline in performance of the task at the end of the relaxation phase. There was some decline after the exercising with water phase. And there was significant decline after the exercising without water phase.

In the exercise with water phase, participants had areas of the brain called ventricles (fluid filled spaces) constrict. Conversely, during the exercise without water phase, the ventricles expanded.

It wasn’t just the expansion or contraction of the ventricles that showed up on the Functional Magnetic Resonance Imaging (fMRI, a type of brain scan), but also changes in the way the brain fired.

The areas of the brain that were needed for the task fired more intensely, and other completely unrelated parts of the brain also fired.The scientists running the study think this may be how the body signals that it’s dehydrated.

So if you find yourself a bit less on-top-of-your-game than usual, ask yourself if you’ve had enough water. And make sure to keep up the liquids when it gets warm, or when you sweat.

Read the study: Exercise‐heat stress with and without water replacement alters brain structures and impairs visuomotor performance.

Dr Carmen Hunwardsen owns and operates Carmen’s Spinal Care, a busy North Brisbane chiropractic clinic in Everton Hills.