Where did the time go and what shall we call it?

When does night begin? When does afternoon end and evening begin? Obviously afternoon is defined just by its name. Morning technically is 12:00 am or zero hundred in military talk but don't most people consider midnight still night? Guess would be to most, morning is when the alarm clock goes off and its time to get up. This brings another unknown into the mix... What about those that work 2nd or 3rd shift? If we go by the technical definition midnight being morning, does that not make the night shorter? Thus making for a long morning? So, when does afternoon end? 

     I say there needs to be more defined times than just AM and PM...