I read Walker's book last fall, and share his view that sleep is profoundly important — even more important than diet and exercise. I say this because diet and exercise will have minimal effects on your body if you are constantly exhausted and it is unlikely you will have the energy to eat well or exercise if you are always tired. Beyond that, sleeplessness has been shown to contribute to chronic illnesses such as dementia, including Alzheimer's disease, cancer, diabetes, heart disease and obesity.
In his book, Walker suggests insomnia is "one of the most pressing and prevalent medical issues facing modern society," yet it is rarely acted on in ways reflecting its importance. He notes the "sleep aid" industry, encompassing prescription sleeping pills and over-the-counter sleep medications, is a $30 billion-a-year industry in the U.S.