Animals including humans use the mechanism of the biological clock to carry out life phenomena adapted to the rotation period of earth. Many researchers focus on the discovery of clock genes, molecular mechanism, and applied science. The cycle of the biological clock is as long as about 24.5 hrs in humans, but some strains of mice are founded to be longer or shorter than 24 hrs. There is a main clock in the suprachiasmatic nucleus of the hypothalamus, brain clock in the cerebral cortex and

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... campus, peripheral clock in the heart liver intestines, lungs and skeletal muscle etc. The main clock is the conductor, and the brain clock and peripheral clock play each instrument and form the harmony of the time axis. Chronobiology is later developed as Chronopharmacology for applications to clinic. Recently, Chrono-nutrition and Chrono-exercise is also developed as interaction study between clock and nutrition, and clock and exercise. There are two sides of chrono-nutrition; (1) the direction in which the circadian clock controls the effects of food and nutrition, and (2) the direction in which food and nutrition affect the phase, amplitude, period of the circadian clock. High fat diet disturbed the circadian rhythm of activity and clock gene expression in the liver. Restricted feeding schedule changed the phase of peripheral clock. Thus, I will discuss the importance of information of chrono-nutrition to keep and use experimental animals. -S 12-