Effects of stress

The essentials

Stress affects people at four levels. Emotional effects include mood swings, anxiety, irritability and depression. Physiological effects include release of hormones such as adrenaline (epinephrine) and noradrenaline (norepinephrine), raised heart rate, blood pressure and blood sugar, and slowed digestion. Cognitive effects include poor concentration, reduced short-term memory and poor decisions. Behavioural effects include disturbed sleep, changed eating habits, increased absenteeism and use of substances. Prolonged stress can lead to burnout, a state of physical, emotional and psychological exhaustion.

Key points

• General Adaptation Syndrome (GAS) by Hans Selye has three stages: alarm reaction (body mobilises resources; the sympathetic nervous system and hormones activate), resistance (the body tries to cope; resources are drawn upon) and exhaustion (resources are depleted; stress-related illness becomes likely).
• The HPA axis (hypothalamus–pituitary–adrenal) releases cortisol during stress.
• Psychoneuroimmunology studies links between the mind, the brain and the immune system.
• Immune cells (white blood cells or leucocytes) include T cells (destroy invaders; helper T cells boost immune response), B cells (produce antibodies) and natural killer cells (fight viruses and tumours).
• Stress, especially long-lasting stress, weakens immune functioning and increases risk of illness.
• Lifestyle: stress can lead to unhealthy habits like smoking, poor diet and lack of exercise, which further harm health.

Exam tips

• Memorise the order of GAS stages: alarm → resistance → exhaustion.
• Know which immune cell does what; questions often test B cells and antibodies.

Common mistakes

• Placing illness in the resistance stage; serious illness is most likely in exhaustion.
• Thinking stress affects only the body; it also affects emotions, thought and behaviour.