does lighting during dark periods affect vegging

my lighting periods are usually pretty hectic because of security reasons, will changing light periods and giving light for like an hour during dark times stunt growth?

its ok if u r in veg u can get away with it.but in flower u cant get away with the lights on during flower as this would send them back in veg mode.u have to stick to the same dark cycle at all times even a light from a timer can send them back to veg mode good luck...........................