This is a vague question. I always pray my vegging clones and plants when the lights come on. They are fluorescent lights and a mist of spray with some azidrachtin and then in between with fresh water is a must in my dry environment to maintain a cool and humid VEGETATIVE area. I have also sprayed plants under 250 watts Metal Halide High Pressure lamps with no ill effects at all. Plants don't get burned up with plain water under fluoros or anything up to a 600 watt even, that's BS. If that was the case you couldn't wet outdoor plants in the sun, it's a myth.
What you doin't want to do is water in the dark cycle. That causes mold, mildew, all kinds of nasty things, I would never recommend foliar in the dark cycle.
I never foliar spray in flower cycle at all. It causes mold too and other issues, you want a dry flower chamber.