24 hours of dark or 24 hours of light will both stress your plants - and that is really the last thing you want to do right now, especially because they're flowering. Overwatering, over feeding.. alright - that's already bad, but messing with the light cycle will really fuck your girls up.
Get a timer.. I can't believe you've reached the flowering stage without using a timer! You must have a hard time sleeping!
-Rich