At what age do babies stop being easily startled?

In general, the startle response in infants gradually disappears after 3 to 5 months.

The "startling" behavior in infants usually refers to the Moro reflex, which is a normal physiological phenomenon. It typically occurs when an infant, while asleep, reacts to sudden sounds in the environment by exhibiting jerking movements of the limbs or body. This phenomenon generally fades away between 3 and 5 months of age. Shortly after birth, an infant's nervous system is still underdeveloped and unfamiliar with many sounds in the world. Therefore, unexpected noises in the environment can easily startle the baby, leading to such startling reactions and possibly causing crying. Parents usually do not need to be overly concerned about this; providing appropriate comfort and reassurance can help the infant calm down and quickly return to sleep.

It should be noted that if the infant continues to frequently exhibit such responses beyond 5 months of age, a medical evaluation at a hospital is recommended to rule out possible neurological disorders.