Very interesting! I had discussed this a little elsewhere and these were two threads I found on the subject. Hmm, food for thought. It is nice to see the tank on in the morning but not essential.
http://www.plantedtank.net/forums/10-lighting/142652-lighting-siesta.html#/forumsite/20495/topics/142652?page=1
http://www.barrreport.com/forum/barr-report/general-plant-topics/4901-split-photo-period-siesta-pros-cons
http://www.plantedtank.net/forums/10-lighting/142652-lighting-siesta.html#/forumsite/20495/topics/142652?page=1
http://www.barrreport.com/forum/barr-report/general-plant-topics/4901-split-photo-period-siesta-pros-cons