The stress response should be regarded as an alarm system, occurring whenever there is something missing. Lack of information (uncertainty), and the absence or loss of control produce alarm, presence of information and control (coping), or cognitive defence mechanisms (distorted stimulus expectancies) reduce the alarm. Both immune and endocrine parameters of stress are dampened by defence and coping. Biologically, these two mechanisms have different time axes. While coping is related to the fast catecholamine response, defence is related to the slower pituitary-adrenal response. The role of cortisol seems to be to suppress and dampen the acute stress response in the later phase, once it has been elicited. The relation between stress and health depends on the stress-dampening mechanisms, on how the alarm is turned off, why it sometimes seems to be left on, and what the consequences really are of leaving the alarm on.