Hmm… surprisingly sparse. Some chronobiology labs have good outlines. YouTube has a few good videos, including some from the Royal Society Lectures that walk you through the basics of the clock, this one especially:

https://youtu.be/KZJAmcpc9SE?is=5XZvvDQwLMC_rIdv

A book recommendation:

Internal Time — Till Roenneberg

Papers: 1. https://physoc.onlinelibrary.wiley.com/doi/epdf/10.1113/expp...

Somewhat old, but still a good systems level review. We know some of this stuff to higher resolution now.

2. https://pmc.ncbi.nlm.nih.gov/articles/PMC7202392/

This one is a very approachable one on sleep and rhythms, and especially talks about why mental health disorders and sleep disruption tend to co-occur.