It no longer makes sense to speak of "feeding problems" or "sleep problems" or "negative behavior" is if they were distinct categories, but to speak of "problems of development" and to search for the meaning of feeding and sleep disturbances or behavior disorders in the developmental phase which has produced them.
Selma H. Fraiberg (2015). “The Magic Years: Understanding and Handling the Problems of Early Childhood”, p.76, Simon and Schuster
