I wish I could say more nice things about this book but the narration  has changed drastically towards the end and I ended up gliding through  pages instead of reading. Walker is a sleep scientist determined to find  out why we sleep and what happens if we don't sleep enough. During the  first half of the book, he successfully builds a compelling argument  towards why sleep is important for us and I was completely blown away  with the science. Sleep is the natural remedy to most of the biological  problems that we currently face. It improves memory, relieves us from  painful memories, improves our creativity, makes us emotionally stable,  protects us from infection by boosting the immune system, repairs our  cells, decreases the chance of getting a heart attack or cancer. There  is no other medicine in the world that can do all of these things  without side effects . Indeed, natural evolution is a miracle.

I  had two major issues with the book. One is using anecdotal evidence to  draw conclusions that are not backed by the scientific scrutiny. For  example, Walker uses evolution to explain how children could have  evolved a shifted circadian rhythm, this argument is very silly and not  backed with any research. The second issue is the alarming narrative  that Walker chose in the second half where the book becomes completely  preachy, borderline scary. Of course, sleep is important but I don't  want that to be written in every sentence. It is repetitive and boring.

I  was disappointed because Walker is an extremely good scientist. If he  steered away from these anecdotal evidences and struck to his science,  this book would have been much better. Overall, a decent read. You could  also read a small article that summarizes all the findings and be done  with it. This book took a lot of time to give the same message.