“…Frequent anomalies of circadian rhythm concerning the urinary excretion of corticosteroids catabolites have been found in old age [10,12], and yet plasma cortisol rhythm seems to remain normal [2,[13][14][15][16], Circadian adrenocortical rhythm is usually present in localized or diffuse cerebral lesions unless they specifically involve neuroendocrine structures regulating corticotrophic releasing factor (CRF) and ACTH [2,6], However, different findings have been reported in the literature on adrenocortical rhythm in blind subjects [1,5,7,9,11,17,18]. For many years we have investigated the circadian rhythm of plasma cortisol in the aged by a macrosopic analysis [1,2,13], and recently the data collected by us have been evaluated by means of the microscopic analysis carried out in the Cronobiology laboratories of Minneapolis, Minn., using the Cosinor method as suggested by H alberg et al [3,4], These authors have set up a technique for the study of biorhythms by computer, this technique is now widely accepted and used in chronobiological research.…”