Hi,
my nurse asks me to do tests at 3am occasionally, especially as i'm on an insulin pump.
It's important so you have an idea whats happening overnight, you may catch a hypo that you wouldn't usually so it can be very useful, you could also maybe see she may be going higher in the night but dropping back down before she wakes up and thats something you also want to avoid.
My nurse usually suggest i do this only a few days at a time, and doesn't demand i do it, just suggests it's a good idea and quite beneficial so i would say a few nights of disturbed sleep wouldn't be too bad if you were to see something unusual.