Babies’ sleep develops in very different ways. Some babies are awake through the night at just 8 weeks, while others aren’t ready until they’re several months old. So how exactly do the sleep stages develop from birth to age 3?

According to experts, parents should train their children to sleep alone completely when they are 3 years old. However, the decision of when to let your child sleep alone depends on the child's health and psychology, as well as the situation and your feelings when having to sleep alone with your child.