Chronobiological processes are integral to the physiology of all living cells and organisms and among the most crucial is the rest/activity cycle. The proper regulation of sleep is critical to normal brain function and undoubtedly underlies the pathophysiology of a number of disorders in man amongst which affective disorders remain the most prominent. While significant advances have been made in our understanding of sleep physiology and most recently genetics in both animal models and man, we still have a long road ahead of us. This symposium organized with Chris Gillin represents a tribute not only to his contributions and that of his laboratory to this field, but recognizes the interdisciplinary synergy that has been developing in the research arena over the years. The underlying biology of sleep processes, its role in diseases of complex behavior, and the potential for refining the specificity for pharmacological targeting and modulation of sleep are the fundamental outcomes of this area of research. We are pleased we could participate in this symposium and as thoughtfully outlined in Chris' Introduction, we know the readership will sense the emerging importance of such investigations in the coming years.