Criticism
of crying it out and sleep training: Though CIO critics sometimes point to a 2012 study finding that babies»
levels of the stress hormone cortisol remained high even after they stopped
crying and went to sleep on their own, that study has since been under fire for being too small (just 25 babies ages 4 to 10 months old) and flawed because there was no control group and no baseline cortisol
levels reported to define what study
author Dr. Wendy Middlemiss
of the University
of North Texas meant by «high.»