Sometimes pts are waiting in the ER for the doctors to c and waiting for consults and admission or transfer orders, so they will just come anytime whenever they r ready. Hospitals are 24 hrs 7 days.
The good thing about night shift is that most of the time it's more quiet compare to day shift. In day shift the doctors, family, physio, everyone is there, asking questions, rounds, etc.
But the down side is that when there is an emergency u get less help, and a good team is crucial, so everyone works together and helps each other.