Well... I feel this isn't a good idea either...
My reasoning behind this is because there would be too many limits on the players. You can only play a certain amount of hours? Whoa... that's WAY bad for business. Players won't like that, players won't pay for that, thus programmers won't make it that way. It limits your fun.
Also, this is slightly more realistic. People make night attacks for the sole purpose of surprise and lack of opposition. If you're asleep in bed, you can bet your base isn't safe. And when they're asleep, same goes for them.
