How do they know?

I would really like to know how my children, mainly my youngest, know what nights end in mornings where we need to be up and someplace at an early time. It seems that the days that just involve us staying home are the ones where they sleep in and sleep the whole night before, but heaven forbid the ones where we have plans should be the same. Today, was a morning where we had plans and sure enough my youngest (10 months) was up at 11ish acting as if I had never fed him in his life, again up at  3 wanting to be fed and then up yet again at 4 for reasons that I may never know but those reasons kept us awake until my hubby's alarm went off at 5:30. I currently can barely function as a human being so I am not sure how my little night owl's expect me to function as a parent. Well, I must conquer this day with my sleep deprived brain and thank God for the creation of Netflix streaming, my Keurig coffee maker and food that does not need my involvement to me consumed by children under three.