I have a question based on psychological illnesses... in a way. Is there such thing as an illness that isn't based on actual health/medical issues but where a person adopts real symptoms but the base or source of these symptoms is a longing or desire. For example in the story Heidi, heidi cannot bare with the pain of being separated from her grandfather, she starts to grow ill and the doctor claims she cannot get better unless she sees her grandfather/ fulfills her desire. Is there any actual sicknesses that are around this description?? Like psychological illnesses, you know? Almost like false pregnancy but not pregnancy... illness... lol 
thanks in advance!
thanks in advance!