The let down reflex, also known as the milk ejection reflex, is a natural physiological response in breastfeeding mothers that allows milk to be released from the alveoli in the mammary glands. This reflex is crucial for successful breastfeeding as it ensures that the baby receives adequate milk during feeding sessions. The process is primarily controlled by the hormone oxytocin, which is produced in the hypothalamus and released by the posterior pituitary gland.