My immediate reaction to reading the chapters in this book is shame. Generations of researchers have studied the psychological and social lives of adolescents, and their main tools have been time-use studies. Among numerous examples, how much time each day or week does the adolescent spend watching television, hanging out with friends, or engaging in extracurricular activities? What is the relation of such time expenditures to measures of academic performance, deviance, or other indicators of adolescent functioning?

The emphasis has been completely on the waking hours, and this book impressively underscores the importance of hours spent sleeping. An undergraduate friend, with whom I had discussed some of the findings in various chapters, immediately provided a real-life illustration of the interaction between the physiological imperatives of sleep and the social perceptions by which we structure our lives. She had been accustomed to staying up very late and sleepily forcing herself to attend her morning classes. In general, she found Stanford professors boring. Now she is getting more sleep and finding her teachers more interesting.

A constant theme of life in society is determining the causes of the phenomena we perceive. Often, there is a choice to be made between internal causes and external causes. For example, I was once feeling sick in Guatemala City and, feeling dizzy, I decided that I was even sicker than I had believed. I was one of the few persons who was relieved to discover that I was experiencing a minor earthquake.