A prospective, monocentric observational study was carried out at the internal intensive care unit I at Universitätsklinikum Halle. We recorded time series of selected scores, laboratory values, and heart rate variability data of 236 consecutive patients. Special focus was laid on differences between geriatric and non-geriatric patients. The essential difference between a geriatric and a non-geriatric patient from a medical point of view is the latter’s worse adaptability of his organ systems to changing conditions (homoiostenosis). The strongest effect observed in this study is, however, a better heart rate variability for geriatric patients. In opposition to the expectation of slower convalescence of geriatric patients due to homoiostenosis, only small differences between the two collectives were observed. In particular, no significant difference in the quickness of score value improvement due to treatment between the two collectives was observed.