Currently in the second year of a happy PhD in France. Looking at other PhD-students around me I would say that those that have few results so far are indeed s

Currently in the second year of a happy PhD in France. Looking at other PhD-students around me I would say that those that have few results so far are indeed stressed, but clearly not to those levels, and that the main criteria for their well-being is the quality of their relation with their advisor (if you intend to do a PhD, pick your advisor carefully, you will work with him for the next three+ years of your life). A factor might be that our PhD tend to be shorter (three years) and that students are paid and have no debts (at least for a PhD in science in France, those don't hold for other fields such as literature).