Female Rat Chewing Cage Bars

Question
I have two female rats , one about just over a year old and the other maybe 8 month old. Well the older one chews the wire cage bars late at night/early morning while I'm trying to sleep and it keeps up later because I have to have quiet to sleep. How can I stop her from doing that? The other one does not do it so I don't know why she does.

Answer
Rats that are high energy and bored will do this. How much play time does she get daily?
Even if the other rat is content, each rat is different and the bar biter is bored. I have had several of them and its pretty annoying, I know, but hard to break until you figure out what it is they are trying to tell you.  Usually they need more time out of the cage at night, enough time so that they are ready to be put back in the cage.  I keep my hyper young males out until they are tired and dont feel like running around their play area. They find a place to curl up and lay down at and this is my cue that they have had enough play time and are ready to go back in their cage. They almost always dont mind being put back in the cage and usually are ready to  go to sleep for the night after that.  If your rat fights you when you put her back in the cage after play time, she didnt have enough time out and is still over stimulated.  Females are much more high strung and have a higer energy level than males too, so this is not uncommon for females, esp at her age.