[Chronobiology in medicine and surgery].

Chronobiology studies predictable variations, rhythms and trends in all forms of life. Each physiologic variable or system in an organism has a time structure which is genetically anchored and capable of being expressed in the absence of external cycles. However, it is normally adjusted by geophysical changes. Chronobiology quantifies rhythms by providing measures of amplitude and timing (phase and period), and a mean more precise than the arithmetic mean. The correct measurement of biological rhythms has led to considerable advances in the understanding of their underlying mechanisms of generation and expression. The use of information on rhythms is opening new opportunities in the prevention, diagnosis and treatment of disease. Chronobiology is also effective in the improvement of the quality of life by teaching self-help to the healthy individual.