Do they (your children) seem to have any issues? Not sleeping well or grouchy the next day or nightmares? Just wondering why you are questioning your decision to let them fall asleep with the tv. I have heard about the melatonin issue, but i also believe our melatonin has been messed up since the invention of the light bulb. We stay up way later than people used to when there was no light bulb. Anyway, is it 'good' for them? I doubt it. But are they having notable issues? I think the stimulation to their brain is possibly harmful. TV is fast moving, fast talking...the screen changes every second or two. That kind of stimulation at bedtime can disrupt their sleep. Do you turn it off as soon as they are out or is it running all night? If you want to transition them out of it, you could see if they sell (or maybe it's on satellite somewhere) a dvd that is an ocean with ocean noise or some sort of nature dvd. Something that is calming until they get used to falling asleep without tv. If they have been do this for a long time, it will be a tough habit to help them break. Good luck!