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Without sounding overly complicated for the layman, Matthew Walker puts his collaborative scientific research forward to make for one of the most compelling arguments why sleep is crucial across all ages for the human mind and body. Most societies grossly undervalue the simple act of sleep. It is a well-written book that keeps the reader wanting to know more. There are many eye-opening chapters such as the link between sleep deprivation and dementia, physiological harm and effect on the immune system etc. Matthew takes evidence from international researchers that compliment his own work, and makes strong scientific arguments for benefits of proper sleep. He takes the time in the opening chapters to explain why it is that we sleep in the first place, and the evolution of sleep which is equally fascinating. This book completely changed the way I look at sleep and is great for anyone wanting to learn about it generally, sleep disorders, or how you can make small changes to improve your short/long-term mental and physical health.