Social media truly never does sleep but what I find is that social media is very reactive. You have to put out to get back so at some point, usually late at night, you simply have to put a hard stop in place. That is hard for me since I am a content producer on Twitter and since I think in 140 characters naturally I am always spitting out content. Since I have come to realize that I can survive on 4 hours sleep for many nights in a row, but anything less than that does not work, I know I cannot carve anymore time out of the day, so 2am is usually my hard stop when I find myself going overboard.
Order and consistency is all in how you perceive what you are doing and how you maintain your connection to what is important. My personal brand, and who I am, is all about being responsive and creating trust and relationships. So I find the social media world, and all the connectivity it affords, a perfect medium for maintaining connection and consistency.