In Idle minds L.M. Frank writes about what happens inside our brains when we’re not actively working on or thinking about something:

Some researchers now think that resting-state networks may prime the brain to respond to stimuli. “The system is not sitting there doing nothing and waiting,” says [Andreas Kleinschmidt, director of research at the French National Institute of Health and Medical Research’s Cognitive Neuroimaging Unit]. Cycling activity in these networks may be helping the brain to use past experiences to inform its decisions. “It’s incredibly computationally demanding to calculate everything on the fly,” says Maurizio Corbetta at Washington University School of Medicine in St. Louis. “If I have ongoing patterns that are guessing what’s going to happen next in my life, then I don’t have to compute everything.” He likens the activity to the idling of a vehicle. “If your car is ready to go, you can leave faster than if you have to turn on the engine.”

It makes intuitive sense that we can’t just continue to create and consume information — our brains need time to process it all. And yet we still so often celebrate 80-hour weeks and shun “downtime” because we’re so afraid of not being productive. It seems like we’re doing ourselves more harm than good if we don’t give our brains time to be idle.