> wonder if there's also a case for reducing our need for more stimuli (e.g. with mindfulness or meditation)

A study was done in Australia ten years ago on a type of meditation that encourages you to be more mindful to see what effect it can have on ADHD. Children were able to reduce or even cut out their medication completely after completing the meditation program.

http://ccp.sagepub.com/content/9/4/479.abstract

http://www.m.sahajayogaportal.org/papers/manocha.pdf (non-paywall link)