In Monster, why is it said that it is best to cry at night while someone is screaming?

Steve states that the best time to cry is at night
because, normally, someone is being attacked and if the noise of the attack is loud
enough no one would be able to hear you cry.  Steve is fearful that if someone hears you
cry that you will be seen as weak and that you will be the next one to get attacked. 
Steve knows that jail/prison is a place full of violence, that he does not being here,
and showing any weakness will cause him problems with the other
inmates.