Late to the party this morning but when you all were getting your beauty sleep, i was still at office.  Calling it a night at 4:00 a.m. is pretty routine for me.  I consider from about 11:00 pm on my time to catch up on things, answer emails, etc. and those are my most productive hours.  I'm a one person office and during "normal" hours, those pesky phone calls, texts, and knocks on the door keep getting in the way of getting much done without interruption.