What does stress do to the body? Our organism has two major hormonal stress systems, the quick responding (within milliseconds) autonomic nervous system, which controls the release of noradrenaline and adrenaline, and the somewhat slower hypothalamus-pituitary-adrenocortical (HPA) system, which is responsible for the release of cortisol, the ‘stress hormone’. Roughly speaking, the quick system prepares us to react immediately whereas the slow system’s reaction depends on the perceived danger of the situation. Noradrenaline and adrenaline increase the heart rate and decrease the heart rate variability, dilate the respiratory airways and activate blood platelets to coagulate. Cortisol antagonises insulin and thus, under certain conditions of persistent stress-dependent dysregulation of the HPA system, results in a diabetes-like metabolic situation. It restructures body fat, promotes obesity, suppresses the immune system and may have a toxic effect on neurons in certain brain regions, particularly the hippocampus, which is important for memory functions. Repeated exposure to social stress in rats leads to abnormal processing of the so-called ‘TAU protein’ in the hippocampus, a mechanism that plays an important role in the development of Alzheimer’s disease. Stress also leads to the shortening of the ‘protection caps’ at both ends of our chromosomes, called telomeres. At the same time, stress also weakens the enzyme responsible for repairing these protection caps. When the telomeres get too short the cell can no longer divide and the tissue loses its regeneration capacity. The result is premature ageing of the organism.