People typically use this saying when someone has basically “tuned out” everything around them and appears to be thinking. Did you ever wonder why after a most taxing day of being “deep in thought” you are basically wasted, spent, exhausted? Yes, another study, researchers looking for something fascinating to discuss with us, right? Well, this really is quite interesting, the study found that when you engage in prolonged periods of mentally taxing activities, a toxic by-product (glutamate) builds up in the prefrontal cortex of the brain where decisions and choices are made.  

A little anatomy lesson, the prefrontal cortex of the brain is critical to our daily activities, a buildup of this toxic substance can prevent us from either making difficult decisions or worse, cause us to make bad choices. Sadly, the prefrontal cortex is highly susceptible to toxic accumulation, thus explaining why at the end of an especially tough workday, we are mentally fatigued. That said, our brains are amazing, will identify when we are mentally fatigued and will compensate for the toxic buildup, shifting us toward easy actions that require little to no effort.  

If you notice that you are experiencing difficulty with cognitive control, it is likely a signal that the brain has a need to get rid of potentially toxic substances that accumulate during mentally taxing activities. So, is there any good news? Yes! For you “long-sleepers”, evidence suggests that these toxins are eliminated during sleep! The takeaway from this study is that you should avoid making important decisions when you are tired. You can still order your pizza with everything on it, not an important decision for most of us! Listen to your body, if you are fatigued, rest, sleep, daydream, whatever activity allows your brain to rest! Stay informed and stay well!