Dr. Ferber was the one of the first widely read authors to advocate for the “cry it out” method in 1985. This book, in its second edition, is more than an explanation of how to use the “cry it out” method. The book is very long and explains more about sleep research, how to develop good habits, and possible challenges. The second edition describes well the method and reasoning, but ultimately advocates allowing your child to cry themselves to sleep while you check in.