Besides the obvious question of 'does it work' I see a myriad of other problems with this. Does Facebook have the internal procedures in place to prevent abuse? Will this data ultimately be used to advertise things like anti-depressants at people? I already get ads for "mindfulness apps" and other BS cures (I dont doubt the principle technique as such, but these things are pretty useless and just techies cashing in on a fad IMHO).