Cry it out sleep training is a controversial approach that involves allowing a baby to cry themselves to sleep. While some parents swear by this method, others worry that it can have harmful effects on a child's emotional well-being. Research suggests that cry it out sleep training does not cause long-term harm, but it can lead to short-term stress and disrupt the parent-child bond. Ultimately, the decision to use this method is a personal one, and parents should weigh the potential benefits and risks before choosing cry it out sleep training.