What days to log sex?

Okay, so when you BD after midnight, do you log it under the day you were awake, or do you put it as the next day? So if you were awake all day today (1/14), had sex at 1 am, and then went to bed (1/15) would you put it under the 14th or 15th? I always put it under the day that I was awake for.