The most important aspect of the study, Weinraub said, is that both sleep training techniques seem safe for babies in the short and long term.The researchers found that the levels of cortisol, a stress hormone, were lower in the babies during sleep training interventions.Moreover, one year after the interventions, the babies did not show signs of being more attached to their parents, nor did their parents report more behavioral problems compared with the babies in the control group.
"Parents have been told by some experts that children's stress levels will increase over time with these techniques and they will have behavioral problems, and this study shows very clearly, which I think is the first to do so, that there are no (poor) effects on children's stress levels and ... children in the intervention groups show less stress than children in the control condition," Weinraub said.