A 2006 review of sleep-training studies, which included thirteen different interventions, noted the following: “Adverse secondary effects as the result of participating in behaviorally based sleep programs were not identified in any of the studies. On the contrary, infants who participated in sleep interventions were found to be more secure, predictable, less irritable, and to cry and fuss less following treatment.”9 (Translation: Nothing bad happened in any study, and in most cases, the babies seemed happier after sleep training than before.) More recent studies draw the same conclusion.10
