"The content on r/ShowerThoughts is quite diverse," /u/IranianGenius, of the subreddit's moderators, told Bored Panda. "The shower thoughts that get more recognition tend to be more unique, yet indicative of the human experience. They are often topical."
The moderator believes that r/ShowerThoughts has become so big because many people are introverts, or have an otherwise introverted side that tends to let the mind wander. "I think the interrelatedness between our realities allows our thoughts to often be similar and merge, and that helps with the popularity of the subreddit."
Interestingly, there haven't been a lot of experiments on why we get such random insights. However, WIRED presented one theory, describing a mental state that could provoke them: the default mode network.
"You become less aware of your environment and more aware of your internal thoughts,” said John Kounios, a psychologist who studies creativity and distraction at Drexel University in Philadelphia.
These activities are physically or mentally demanding, but only on a mild level. They also need to be familiar or comfortable enough that a person stays engaged but doesn't get bored, and last long enough to allow an uninterrupted stream of thought.
Kounios said that our brains typically catalog things by their context: windows are parts of buildings, the stars belong in the night sky, and so on. Ideas will always mingle to some degree, but when we’re focused on a specific task our thinking tends to be linear.
To explain this process, the psychologist likes to use this example: imagine that you have a stack of bricks in your yard and you walk by them every day. You hardly give them a second thought, right? And if asked, you'd describe them as a building material. However, one day in the shower, something makes you think of your neighbor's walnut tree, and all the nuts that have been falling in your yard. They probably are very tasty. Boom, you realize that you can smash those nuts open using the bricks in your yard.
The bricks may not be the best nutcrackers in your house, but this example perfectly illustrates how the default mode network frees the things in your brain from external associations.
