This will cause major problems with your plants. Maintaining a consistent light schedule is absolutely critical to produce the highest quantity and quality buds. Especially during the flowering cycle, an erratic light schedule will most certainly stress the shit out of the plants and will most likely lead to small, underdeveloped buds and more likely, hermaphrodite flowers which will seed your crop. I cannot stress enough how important it is to maintain a consistent light schedule and 12hr uninterrupted dark period. You have to keep in mind that the uninterrupted dark period is what signals the plant to begin flowering and producing buds. If you are unable to guarantee 12 hours of uninterrupted darkness (COMPLETE DARKNESS!) every single day with no exceptions, then you might as well throw your plants out and find a new hobby. Yes, it's THAT important.