i'm not half as cautious as most people here, my mobile phone gets put on charge by my bed side every night, my itaste vv is charged over night also, these are no different to actual batteries in a charger, yes shit happens, i heard about a galaxy s3 phone exploding in someones pocket once, and yes do preventative steps to stop this happening as much as you can with safe chargers and good batteries, theres a whole line of defence between you and catastrophe, fuses, safety cut out on chargers, safe chemestry batteries, fuses, etc. at the end of the day its up to you how "careful" you want to be, if you can sleep easy with things on charge go for it, if not dont
I think using spare battery's is the way to be far, its easier to spend a few queens heads on some kit then replace the house as its burnt down. cheers people good advice from both sides of the fence but i think safety wins on this one.
I do sleep with my phone charging overnight, have done as long as I can remember but for some reason I won't leave my e cig battery on charge overnight! I do make use of a few spares in rotation and normally charge them in the evening before bed/in the morning or at work, save a bit on the bills with the latter as well