hälytysreaktion

Hälytysreaktion, or the alarm reaction, is a physiological response triggered by the body in reaction to stress or perceived threats. It is the first stage of the general adaptation syndrome (GAS), a concept introduced by endocrinologist Hans Selye in the 1930s. This reaction is mediated primarily by the sympathetic nervous system and the release of stress hormones, such as adrenaline and cortisol.

When an individual encounters a stressful situation, the hypothalamus activates the sympathetic nervous system, leading to the release of catecholamines—primarily adrenaline—from the adrenal medulla. This surge of hormones prepares the body for a "fight-or-flight" response, increasing heart rate, elevating blood pressure, and redirecting blood flow to essential muscles. Simultaneously, the adrenal cortex releases cortisol, which mobilizes energy stores and suppresses non-essential functions like digestion and immune responses.

The alarm reaction is characterized by heightened arousal, where the body temporarily shifts resources to address the perceived threat. While this response can be adaptive in acute, life-threatening situations, prolonged or repeated activation may lead to negative health effects, such as chronic stress, fatigue, or weakened immunity. The duration of this stage varies depending on the intensity and duration of the stressor, with some individuals experiencing a rapid return to homeostasis, while others may become stuck in a prolonged state of heightened alertness.

This phase is distinct from the subsequent stages of GAS—resistance and exhaustion—where the body either adapts to the stressor or becomes depleted. Understanding the alarm reaction helps in recognizing the body’s immediate stress response and managing its effects through relaxation techniques, lifestyle adjustments, or, in chronic cases, professional intervention.