Attention Restoration Theory which proposes that when we are doing an activity which required our direct attention (like studying) we often take study breaks the wrong way; we go on Facebook or text friends. However, A.R.T. suggests we should instead do something like walking in a park or just looking out th window onto a natural scene.
This method of recharging our attention span has been found to be highly effective in both the general population and those diagnosed with ADHD which is a fascinating result!
See Kaplan's (1995) article for more detail :) The Restorative Benefits of Nature