Is There a Seven Day Week?

i was wondering if there is anything that might connect the idea of a seven day week to the the biological world, particularly to human biology. And i found an interesting, and at times, perplexing, paper that was published in 20 16 in the journal of chrono biology international. It aims to look at the seven day domain of the biological time structure with special reference to human beings. So it seems like they are investigating exactly the question we just raised. Like, right? Could there be any kind of rhythm within the body? Of things that tend to happen in cycles of seven days or so?"