As emotion goes up, intelligence goes down

Our brain kicks into overdrive when we experience intense emotion. Considering it consumes 20% of our energy on a normal day, in overdrive it is really working.

Anxiety, stress and other intense emotions trigger biochemical processes that prevent neurons from talking to one another. This is why it is difficult to think clearly and remember things when experiencing emotional distress.

Unless we calm ourselves we cannot deal effectively with difficult situations.
Some leaders derail because of this very trait. They have not learnt to process their emotions. In fact, as a society we are not good at processing negative emotions. We tend to ignore it (by visiting Mars or a cave if you are male) which leads to suboptimal interpersonal behaviour.

Finding your strategy to process negative emotion is a key skill for successful leaders. Unfortunately, its not all glory and light at the top of the tree. It's where the storm hits most ferociously.