[Chronobiological approach of aging].

Ageing is a complex, multifactorial phenomenon. The existence of biologic rhythms as well as the study of their modifications or their alteration in the aged are useful and pertinent to understand the biologic age. 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 ageing is worth quantifying. This paper rounds up the question.