Any physical or psychological stimuli that disrupt homeostasis result in a stress response. The stimuli are called stressors, and physiological and behavioral changes in response to exposure to stressors constitute the stress response. A stress response is mediated through a complex interplay of nervous, endocrine, and immune mechanisms, activating the sympathetic-adreno-medullar (SAM) axis, the hypothalamic-pituitary-adrenal (HPA) axis, and the immune system. The stress response is adaptive to prepare the body to handle the challenges presented by an internal or external environmental challenge, such as stressors. For example, the body's physiological responses to trauma and invasive surgery serve to attenuate further tissue damage. Suppose the exposure to a stressor is actually or perceived as intense, repetitive (repeated acute stress), or prolonged (chronic stress). In that case, the stress response is maladaptive and detrimental to physiology. Exposure to chronic stressors can cause maladaptive reactions, including depression, anxiety, cognitive impairment, and heart disease.

Not all forms of stress are detrimental. Some stressors are enjoyable, stimulating, and inspiring. Termed eustress, these positive stressors replenish our energy, enhance cardiovascular health, boost endurance, and sharpen cognitive function. Eustress fosters mental acuity and motivation. In contrast, distress is characterized by adverse effects on the body and mind.

Stress is categorized into various types based on duration, source, and response.

1. Acute stress: The short-term stress that typically results from immediate stressors or challenging situations. The body's fight-or-flight response leads to temporary physiological changes such as increased heart rate and adrenaline release.

1. Chronic stress: This occurs when the stressor persists over an extended period. Prolonged exposure to chronic stress can lead to cumulative physiological and psychological effects, increasing the risk of health problems such as cardiovascular disease, anxiety, and depression.

1. Episodic acute stress: The stress occurs when individuals experience frequent episodes of acute stress. This pattern may be characteristic of individuals who lead chaotic or disorganized lifestyles, constantly facing deadlines, commitments, or interpersonal conflicts. The cycle of stress exacerbates health issues and impairs daily functioning.

1. Traumatic stress: This type results from exposure to traumatic events, such as natural disasters, accidents, or violent acts. The trauma overwhelms an individual's ability to cope and may lead to symptoms of posttraumatic stress disorder (PTSD), including intrusive memories, avoidance behaviors, and hyperarousal.

1. Environmental stress: This type arises from adverse or challenging conditions in one's surroundings, including noise, pollution, overcrowding, or unsafe living conditions. These stressors can have detrimental effects on physical and mental health, contributing to a sense of discomfort or unease.

1. Psychological stress: The stress stems from cognitive or emotional factors, such as perceived threats, worries, or negative thoughts. Typical stressors include work-related pressures, academic expectations, social comparisons, or self-imposed demands. Manifestations include anxiety, rumination, or perfectionism.

1. Physiological stress: Physiological stress refers to the body's response to internal or external stressors that disrupt homeostasis. Examples include illness, injury, sleep deprivation, or nutritional deficiencies, which activate physiological stress pathways and compromise health and well-being.