Today, when I visited the service records page in dataone.in, I found that my usage excluding night unlimited was half that of total 24 hour usage. Since I done use between 2 AM to 8 AM, I doubt night unlimited is from 8 PM to 8 AM.
It cannot be because if you check your account it clearly mentions that usage during that time has been added up excluding night unlimited. The column which I am talking about is the one at the right extreme where it is 0 when during night time and some values when it is not. You can also see the time of usage. So this is not right. I hope even that will be coming soon.