INTRODUCTION The clinic usefulness of a diagnostic test is in relationship to the precision with which measures the studied phenomenon. The lack of precision involve the reliability upon causing confounded results of the normal and diseased populations. OBJECTIVE Since the sleep varies in function of the age, to find sleep parameters that fit better to the changes that the aging produces in the sleep. MATERIAL AND METHODS Spectral analysis through the Fast Fourier Transformation of the ambulatory EEG of 28 healthy subjects. RESULTS Maximum value of power (maximum depth) in a frequency of ended in a point of the sleep goes losing in a way specifies and systematical with the age. CONCLUSIONS The variance accounted by this parameter is of the 87%, what, being tried to a phenomenon so variable as the sleep, supposes a interesting starting point to be applied to some pathologies in those which is presumed that the slow sleep (to which is attributed a paper in the cerebral restoration) is decreased.