Despite what the title says (my copy, at least, is subtitled "the neuroscience of a good night's rest"), this is mostly a book about narcolepsy, and, to a lesser extent, other sleep disorders. I read out of curiosity about the nature of sleep, and also in the hopes of finding some representation of my own sleep troubles, and while my hopes in that regard were not really fulfilled, I nevertheless found this to be an engaging and informative exploration of how sleep works, the history of its study, and (comprising the bulk of the book) the many ways that it can go wrong. I can't remember the last time I read a science book that had such a strong narrative drive (at least for the first half of the book). The story of Nicholls' own experience with narcolepsy creates the narrative arc, which is then filled with scientific explanation and history, anecdotes, court cases, and, in the case of one of my favorite chapters, the chapter on hypnagogia, literature. It covers a lot of ideas, and many times I felt myself wanting to know more, more detailed explanation of a scientific phenomenon or medical procedure, or more details about the life of a person with a sleep disorder, but we had already jumped to the next thing. It's already a somewhat lengthy book, but I wouldn't have minded the extra pages.
I thought the chapter on sleep deprivation would be really scary, given that I am currently sleep deprived, and I put off reading it for several days, out of fear, but it turned out to be ok, not any scarier than the gaping unknown horror that I imagined when I had previous thought of when I thought about the potential impact of sleep deprivation on health.