When I had my sav... I was always told to give them a day and night that it is good for thier keeping thier moods in check and something to the effect they need a day and night. I used 12on 12 off cycle. I myself would be leary about having a light on 24/7 regardless of what is said based on the fact that in the wild they would not have light 24/7... I would think his rest would not be as restful as it could be if he has a night time.

As far as your monitors weight and length gain, I would not say it is b/c of the light cycle you are currently using...