At midnight I put my phone on silent. If one of my regular clients calls up earlier in the evening and requests a later appointment, that's generally fine. But I will not see new clients after midnight, and I definitely don't take any calls after midnight (generally it's impossible to screen them at that time of night anyway). I agree that the percentage of "problem" clients definitely goes way up after midnight. You should hear some of the voicemails I've received at 3 or 4am, obviously intoxicated, and sometimes belligerent, often other intoxicated individuals can clearly be heard in the background as well. Good way to end up on my personal DNS list before you've actually even talked to me.