CIO, or cry it out, is a controversial subject and one that has been dividing parents for at least 2 decades. But in the opinion of our expert sleep consultants, the larger problem with CIO is that some parents assume ALL sleep training is CIO; they assume that sleep training is just letting your baby cry until he/she stops waking up at night and stops waking early from naps. Cry It Out Is Not Sleep Training You can imagine how frustrating it is for our team to combat this misconception.