I have read that fish and plants need around 10 hours of total and complete darkness; no room lights, nothing. They get this in the tropics of course, so it makes sense their physiology would be geared to that.
I don't know the amount of light it takes to stress out the fish, I do know that once or twice when I have shone a small flashlight into the tank [I had a reason, looking for my new very nocturnal woodcats that only come out in pitch black darkness] the light bothered the characins, who started bumping around. That's not much light.
With plants, I read a while back from one of the botanists that something as minimal as car lights shining through the window will be picked up by plants. Plants react to very minimal light, not to photosynthesize obviously but for other physiological matters. A streetlight over dandelion is sufficient light to make them lose their biological clock (for lack of better words) and they remained up in frost and were killed.
As long as one turns all these things off for a decent period of total darkness, I wold assume it doesn't matter.
Thinkrevolutionx, why don't you just change the light period to be on when you are most likely to be there? Fish and plants don't care if the "daylight" is in the middle of the night, provided they also get the total darkness "night" they need. Have the lights come on later in the morning and keep them on later in the evening. Or use the siesta approach. Either way, you would be able to see the fish properly.