I've been charging my phones overnight beside my bed for years. This is the first time I've ever read something like this so I thought it would be good to pass it on.
It is possible to over charge your phone. If you leave your phone on the charger after is it 100 percent charged it will reduce the capacity of your battery. The more you over charge the less capacity your battery will have. Which means you'll just have to recharge sooner.
Letting your phone go all the way down to zero before you put it on a charger is also bad for the battery too. It will cause it to wear out sooner.
One more thing. Keep your phone in a cool place. An over heated phone is not good either.
With all we can do with our phones these days it would be nice to have a charging station that turns off once the phone is fully charged.