C o n t e n t s Editorial Jean-Paul Macher In this issue Pierre Schulz State of the art Biological clocks and the practice of psychiatry Pierre Schulz (Switzerland) Basic research The daily timing of gene expression and physiology in mammals Ueli Schibler (Switzerland) Quantitative genetics of sleep in inbred mice Mehdi Tafti (Switzerland) A history of chaos theory Christian Oestreicher (Switzerland) Pharmacological aspects The phase shift hypothesis for the circadian component of winter depression Alfred J. Lewy, Jennifer N. Rough, Jeannine B. Songer, Neelam Mishra, Krista Yuhas, Jonathan S. Emens (USA) Clinical research Visual impairment and circadian rhythm disorders Steven W. Lockley, Josephine Arendt, Debra J. Skene (USA, UK) The chronobiology and neurobiology of winter seasonal affective disorder Robert D. Levitan (Canada) Interpersonal and social rhythm therapy: an intervention addressing rhythm dysregulation in bipolar disorder Ellen Frank, Holly A. Swartz, Elaine Boland (USA) The role of circadian clock genes in mental disorders Elaine Waddington Lamont, Daniel Legault-Coutu, Nicolas Cermakian, Diane B. Boivin (Canada) Poster Individuality and stability of nocturnal secretion patterns for eight hor- mones in healthy young men Pierre Schulz, François Curtin, Thierry Steimer (Switzerland) ISSUE COORDINATED BY: Pierre Schulz