overnight useage

[#1]

I note from my broadband useage that I have ablue line saying that Ive used overnight useage.
Im bewilderd  I know that I use my broadband say from 9pm to 11.55pm does this conistude overnight useage?

[#2]

Nope anything after midnight to 8am is overnight.
If it is a small amount then probably just the background traffic from the router -> PN is causing it, If it is GB then something is connected and actively downloading.