What I found interesting was the bit about how the cortisol levels in the baby's brain soar so high when babies are left to cry, and then I read an article today (see the AP News Desk on TheAttachedFamily.com for more information) in which a foster mother saw research that these dangerous cortisol levels in CIO babies reach the level equal to that from a jellyfish sting. Wow! So, those parents who use CIO are causing their babies huge discomfort.
I was never comfortable with CIO, but I had a babysitter once (a relative) who I caught using CIO on my then 9-month-old daughter. I came home and could hear her crying and sobbing before I even got to the front door! I still think about that day and wonder if that caused any emotional damage.