Why sunlight is good for us, and how it can be bad--in far greater detail than most will want or need. Lillyquist, a former psychology professor living in Tucson, has investigated his subject quite thoroughly: he begins with a historical review of societal attitudes towards sunlight (the pendulum swings continually between healthy and unhealthy), and also considers its religious importance. Then he explains exactly what sunlight is, and does: ""The UVR with the shortest wave-lenghts, the UVC, lies between 100 and 286 nm. While the biological effect of this active radiation is considerable, we do not need to be concerned with it. . ."" Pros and cons of exposure follow--going way beyond vitamin D absorption versus skin cancer. (Red blood cells, we learn, fall in number when animals are kept in darkness--and that's just the beginning.) Finally, there is extensive practical advice on sunlight exposure: sun or shade, how much of each, what fabrics to wear, how to take such factors as heat, humidity, and wind into consideration; and much more. Many particulars, and some new information--but not in a form that will appeal to the merely curious or naturally concerned.