If you had a medical release from work resulting from a stressful work environment and upon receiving medical clearance to return to work you discovered that your job duties were changed by your employer, presumably to result in less stress for you, I see nothing at all improper or illegal as to what your employer did.Assuming that upon return to work after your leave of absence the work duties were in fact less stressful for you, I would have to applaud your employer who seemingly tried to make things easier for your upon your return to work.