[The aging of biological rhythms in man].

The characteristics of the rhythms of some biological variables (peak location in the time scale, mean level, amplitude...) may be modified in elderly subjects when compared with young ones in the three spectral fields (ultradian, circadian and infradian). The purpose of this review is to round up the question of such possible modifications with age of endocrine functions (adrenals, gonads, pituitary, parathyroid, pineal, vitamin D...) and of others (body temperature, plasma proteins, cations...). These modifications, if any, may be interpreted as a change in the adaptability of aged subjects to environmental factors. The loss or decrease of adaptation capacity with aging is of course worth quantifying. The concept of biological rhythms has thus to be taken into account in any study dealing with aging.