TIL there's a technical name for why ideas happen in the shower: the "default mode network" is a pattern of brain activity, measurable using fMRI, that happens when we're unfocussed. When the brain goes into idle mode (reduced activity), this part of the brain actually becomes *more* active. What does the default mode network do? Research is ongoing, but part of it definitely seems to be making connections, which is associated with curiosity and creativity.

More here: https://www.nationalgeographic.co.uk/history-and-civilisation/2022/08/the-science-of-why-you-have-great-ideas-in-the-shower