Well, My pc is on since 10.00 or 11.00 am and I turn it off at 2.00 am or 4.00 am. The sites are always opened are www.wordreference.com and www.italki.com but I do my things in the meanwhile. Those are gym, work, house stuff and studies.
I usually go online at night and I spend like four hours chatting.
P.S. Going through the basic, I don't know how many hours I spend here, because it depends on the day, the weather, the mood, and so on. xD