Adding insulation to the atic

I have a hosue that was built in the 1980s. Our upstairs is always way hotter than the rest of the house. I know it will always be that way since heat rises, but I was wondering if adding more insulation to the attic would be worth it? There is about 6-8 inches of just blown-in stuff up there right now. Woudl it be worth it to roll out some more up there? I am also going to spray foam around all the electrical boxes for the lights and what not to help air seal it the best I can. I think that is going to help alot as I know a couple of our closest lights leak a little bit.