Multitasking at work can lower a person’s IQ by ten points, which is equivalent to losing a night’s sleep and twice the effect of smoking marijuana.

Bregman, Peter. "How (and why) to stop multitasking." Harvard Business Review

Dès qu’une personne se fixe deux objectifs simultanément, chacun d’eux est analysé et pris en charge dans un hémisphère du cerveau. Or, il n’existe, par définition, que deux hémisphères. Au-delà de deux buts, le cerveau humain sature et ne semble plus gérer l’information. Évitez d’accomplir trop de tâches à la fois.

As soon as someone sets two objectives at the same time, each one is analyzed and managed in one hemisphere of the brain. However, by definition, there are only two hemispheres in our brains. Beyond two goals, the human brain reaches saturation and does not seem to process information. Avoid accomplishing too much at once.