I highly highly recommend everyone read Deep Work by Cal Newport - http://calnewport.com/books/deep-work/

The key concept Cal talks about that's relevant for this discussion is "attention residue". When you switch from low-stimuli, high-value work that requires deep focus to high-stimuli, shallower work (like meetings), it can take up to 30 minutes to really switch back to focus mode again.

Relevant excerpt on attention residue - https://hackernoon.com/excerpted-from-deep-work-by-cal-newpo...