Daydreaming is taken very seriously within scientific circles, where it is more accurately referred to as mind wandering. The level of interest in this area runs more or less parallel to that of the default network, and that is no coincidence either. The neural activity that can be observed when a person is daydreaming is very similar to that found in the default network. The control situation when taking neural measurements is also one in which the brain is not performing any tasks, and so we start daydreaming. We let our thoughts run free and start associating different memories with each other. – LitHub