A great book to start the year! We often take sleep for granted and trade it for more screen time and not-so important mundane tasks in todays world. This book presents lots of facts and data backed by science and research to remind us how crucial sleep is to our physical and mental fitness. Chapters about different sleep phases (REM and Non-REM), things that happen in our brain and body during those phases, sleep impact on learning and retaining, impact of sleep on brain development as we grow from baby to adult, etc. were quite fascinating to read. It also offers information on many ways to improve our sleep quality. Walker quoted lot of his own research study and experiments at various places in the book that became little boring at times. I felt it little lengthy, but nonetheless, a satisfying read. I’ll definitely read it again sometime soon.