Multitasking
It is especially difficult to concentrate when there are many tasks and all of them are important. Where's the legendary multitasking when you need it? (and all the hiring managers of this world)? But the fact is that it simply does not exist. Researchers found out, that it is difficult for the brain to concentrate even on two things at the same time. And when several important tasks come into focus, the body panics and releases cortisol and adrenaline - “stress hormones”. Because of this, we work inattentively: we make mistakes and get tired quickly.
Dopamine
Everything is clear with stress hormones, but then it gets even more interesting. The exact opposite of stress, dopamine, is also involved in our inability to concentrate. This substance is involved in the brain's reward system. What does it have to do with it? We are often distracted from an important task by something more “pleasant” for the brain. For example, look at likes on social networks. At this time, dopamine is released - and we feel pleasure. It turns out to be a vicious circle: the more distracted you are, the more pleasure you get.