People daydream to help explore their inner experiences. Daydreams help process past experiences and allow people to imagine future events to help understand others and make moral decisions.
The brain's "default network" makes daydreaming possible by linking parts of the frontal cortex, the limbic system and various other cortical areas that are involved in sensory experiences. When the default network is active, it generates its own stimulation known as "stimulus independent thought," which makes up daydreams. Other parts of the brain are turned off during a daydream, which can cause memory loss and make it difficult to stay on task.