[General introduction to clinical chronobiology and the therapeutic manipulation of biological rhythms].

In humans, most clinical variables follow biological rhythms approaching to a mathematical function defined by the cosmic-climatic rhythm. Chronophysiology, chronopathology, chronopharmacology, chronotherapy and phototherapy have common elements frequently studied in a disperse manner, thus making it difficult a global understanding of clinical chronobiology as a unitary and well-characterized discipline. This review focuses on medical chronobiology, which is much more technical since it only gathers those directives of clinical chronobiology having a health-care impact on daily practice.