The so-called ‘adrenaline rush’ is an evolutionary, self-defence mechanism, designed to prepare the body for sudden, vigorous action in dangerous, exciting or stressful situations. The mechanism is automatic, or beyond conscious control, but stimulates the adrenal glands, situated above the kidneys, to secret adrenaline, also known as epinephrine. Adrenaline is a hormone, which has specific effects on the organs and tissues of the body. Adrenaline increases heart and lung function, while at the same time dilating the airways and the blood vessels in the skeletal muscles. Consequently, during an adrenaline rush, a person typically experiences an increase in physical strength and performance, sharpened mental focus and a decrease in pain response. Other positive effects of adrenaline include temporary bolstering the immune system and the level of antioxidants in the blood, which combat tissue damage. In small, intermittent doses, adrenaline is considered a healthy hormone, which stimulates the body and mind without any ill effects. Indeed, some people participate in certain activities, including ‘extreme’ sports activities, such as skydiving, bungee jumping, zip lining or cage diving with sharks to deliberately trigger an adrenaline rush, purely because they enjoy the sensation. Of course, if your adrenaline threshold is a little lower, you need not, necessarily, resort to extreme sports to trigger a healthy adrenaline rush. Watching a horror film or visiting a scary, eerie place, such as a supposedly haunted house, can induce a similar reaction. Gambling, too, is a risky, unpredictable activity, which triggers the ‘fight or flight’ response, flooding the bloodstream with stress hormones. So, rather than jumping into thin air, or confronting a great white shark, you might like to think about a social activity, such as an online poker or slot tournament, to induce your adrenalin ‘high’.