Should we trust the eDoctor?

New e-health devices, a huge variety of MindApps, meditation and sleep applications promise to provide biofeedback and battle stress and its dangerous companions. Smart phones and smart watches can measure our body functions and coach us through many stressful situations. How do they work? Can they replace or assist doctors, check soaring health costs, cut down on sick days? How do e-health and its devices work and perform in the general field of health? Do these devices have undesired side effects, such as potential addiction?  Can they make matters worse or even make us hypochondriacs? What do e-health designers, health officials, patient groups and the public say?