Edward Hallowell coined two great terms in his book Crazy Busy: C-state and F-state.
C-state is clear, calm, cool, collected, consistent, concentrated, convivial, careful, curious, creative, courteous, and coordinated.
F-state fractures focus, is frenzied, feckless, flailing, fearful, forgetful, flustered, furious, fractious, feverish, and frantic.
Multitasking leads to F-state and activates different parts of the brain than C-state. Just giving F-state a name and being aware of it helps to back out of it.