Cry it out sleep training, also known as the extinction method, is a controversial sleep training approach where parents allow their babies to cry until they fall asleep without any intervention. This method has been popularized in recent years, with some parents reporting success in getting their babies to sleep through the night. However, the approach has also been criticized for being too harsh and potentially damaging for the baby's mental health. Despite the debate, many parents continue to use this method, and it remains an option for those seeking a solution to their baby's sleep troubles.