Have you considered your air circulation? What type of intake/exhaust system do you have?
If the average temp of your room is in the mid-ninties, you just need to decrease it by a couple of degrees. For super high temps..There is nothing like AC...its expensive, but the difference it could make in your buds may cause you to have a mild stroke! hehe! Nah, but for real you can lower the temp of your room a few degrees by increasing the air circulation. Fan plus a cool air intake is the most inexpensive way to attack it.
Another thing to consider, what time of day do you have your lights on. Because the lights are very hot, turning them on during the coolest time of the day (1am for example) uses nature to your advantage...running 800watt lights in the middle of the day adds to the temp of the room.
As far as a "light cycle disruption"...changing the cycle from 12/12 to 20/4 can cause hermies, but I don't believe that you'll get hermies by changing the intensity of the light from 800watts to 400watts. BUT, if you can avoid reducing your wattage the better, because it makes a difference in the density of your nugs.
