People generally have great ideas in the shower that brings a high level of creativity.
Alice Flaherty, one of the most renowned neuroscientists researching creativity explains that's very important for us to be creative is dopamine. The more dopamine that is released, the more creative we are, she says: "People vary in terms of their level of creative drive to the activity of the dopamine pathways of the limbic system."
Typical triggers for events, that make us feel great and relaxed and therefore give us an increased dopamine flow are taking a warm shower, exercising, driving home, etc. The chances of having great ideas then are a lot higher.
Dopamine alone, which gets triggered in hundreds of events, where we aren't very creative, can't be the only reason. Another crucial factor is a distraction, says Harvard researcher Carson: "In other words, a distraction may provide the break you need to disengage from a fixation on the ineffective solution.''
Lastly, after you have received an influx in dopamine, can be easily distracted by an extremely habitual task like showering or cooking, a relaxed state of mind is absolutely important to be creative, says Jonah Lehrer.
So this seems to be the magic combination: If you are in a relaxed state of mind, easy to distract and full of dopamine, your brain is most likely to give you your best, most creative ideas.