Can you Overcharge and iphone 5?

Hi all, I have a question concerning the battery care of my iphone 5. This is the first iphone I've owned and I was just wondering if it was healthy for the battery to be left charging overnight even after it reaches 100%.

I've been trying to do some research regarding this, but I seem to be finding mixed opinions and apple's battery page seems pretty vague ... So for all of those who might know... is it possible to overcharge the iphone's battery/can i leave it sitting on the charger all night even if i plug it in at 40% and it then sits at 100% for 6 hours??

Thanks.