Decent Exploration Of The Topic. A couple of caveats to this review up front: This book was released in 2019, and I’ve read at least a handful of books on the same general topic of human circadian rhythms both before and since. I also read it via Audible, so I have no way of knowing if its documentation is adequate or lacking. These caveats noted, to me this book was more a decent introduction to the general topic than a truly in depth or ground breaking look at it. Most of the things it covered were things I was already generally aware of and even knew a bit of the specifics of due to those other books. So to me, there truly wasn’t much “new science” here at all. And yet, the book was very much approachable and enjoyable, and indeed seemed great for someone less read in the subject at hand. Geddes herself reads the Audible version, and it is quite clear she both knows her subject well and is genuinely passionate about it, so those are definite bonuses in my take on the book. Overall a truly solid introduction to the topics at hand, told in a very approachable manner even for those less familiar with them. Very much recommended.