4.0

This was an interesting read - very accessible to a general audience. Dr. Walker has spent his career studying sleep - why we need sleep, the consequences of not getting enough sleep. He does a really good job of explaining and lots and lots of studies - and explaining why some of those studies are more valid than others.

There's not much about how to get better sleep - although, his arguments are compelling enough I'm looking into sleep studies for myself and one of my children. He has very strong arguments for making societal changes that would improve our sleep -- flexible work schedules to accommodate different sleep styles (night owls vs. morning larks), later school start times especially for high school, better education about the importance of sleep and dangers of drowsy driving, and better sleep environments for hospital patients.