The science presented in this book is very real and very relevant, sometimes esoteric but mostly boiled down to practical, applicable advice and insight about sleep. Many of the scientific findings cited in the book have links or bibliographic information back to white papers that you can look up, and I appreciated this level of diligence and legitimacy.
Sometimes, the message -- that we as a society treat sleep too lightly -- reads as a call-to-action, and I appreciated the urgency. It also sometimes felt bombastic, histrionic, with language such as "platinum-grade nocturnal service" and "brain feasting on this emotional recalibration" when referring to sleep's functions. As such, the book wasn't easy to read, and I didn't breeze through it since the diction was often too high and rich with exaggeration.
But the meat of the book -- descriptions of scientific studies and their relevance to sleep -- translates well to advice we can apply to sleep, including treatment plans for insomnia like CBT-I (cognitive behavioral therapy for insomnia), ways of educating those around us, ideas for sleep technology, and in-depth studies of why the brain regulates mood/memory/pain better with consistent sleep. I believed in sleep heading into the book, but I still learned a lot about the various parts of the brain, and the reasons each part benefits from specific portions of sleep, deep REM (Rapid Eye Movement) sleep or NREM sleep. The author explained terminology and backed up his claims with tests and citations, some on humans, some on rats.
I could do without all the societal hand-wringing and public policy reform, but I do feel like the book elevates my valuation of how important sleep is, and how we can achieve better sleep through practical methods like temperature regulation, analog reading, and encouraging mind games. Dr. Walker addresses sleep debt, short vs. long-term memory, caffeine, adenosine, and melatonin early in the book, setting the stage for more advice-focused chapters later on. He never properly defines a "sleep spindle," but whatever it is, the book provides a good argument and evidence for improving the quality and number of our sleep spindles through time, consistency, and the proper respect & environment for quality sleep.