Stress and Cortisol. By Juan Carlos Bajanda Benitez. A few days ago I had a work meeting to resolve a problem with a project. This meeting was delayed for several days, and each day the magnitude of the problem increased, at least in my mind, to the point that it kept me awake at night, creating multiple catastrophic scenarios. The scenarios all turned out to be fake, the meeting went smoothly, but the lack of sleep and the constant bad mood were real and tangible. This is how stress works, it is not limited to a mental issue, but acts on our body and causes damage that accumulates and degrades our physical and mental condition. Our cave-dwelling ancestors, who did not yet have a brain as evolved as ours, instead had a very efficient limbic system. This system, located in the hippocampus, is also known as the reptilian brain, since it is similar in many reptiles and other mammals. This system sends alarms to the rest of the body when it detects signs of danger, and these alarms prepare the body to flee or fight. The adrenal medulla secretes large amounts of adrenaline and cortisol necessary to increase our strength, quickness, speed, and concentration needed to survive, but this waste of energy comes at a very high cost. Thanks to this system, our species was able to survive, unlike many other species that did not. This system is still functioning today. The problem is that our body does not differentiate between a real situation and a fictitious or imaginary one, and the secretion of adrenaline affects the body whether or not there is a latent danger. But what are the effects of stress on the body, and why can they be harmful in the long term? Stress triggers a fight or flight response that raises cortisol and adrenaline levels, causing physical and mental damage such as headaches, migraines, fatigue, muscle tension, digestive problems, insomnia, anxiety, cardiac risk, and weakening of the immune system, in addition to many other effects that are not imaginary. According to the Mayo Clinic, these are the main consequences of chronic stress on the human body. Cardiovascular system. It increases heart rate and blood pressure, which in the long term raises the risk of heart attacks or hypertension. Digestive system. It causes nausea, abdominal pain, heartburn, constipation, or diarrhea due to the gut-brain connection. Musculoskeletal system. It generates constant tension in the neck, shoulders, and head, resulting in tension headaches. Immune system. It reduces the immune system, making us more susceptible to colds, flu, and infections. Mental and emotional health. It causes irritability, anxiety, depression, concentration problems, and mental fatigue. Endocrine slash metabolic system. Excess cortisol increases blood sugar and can lead to obesity or diabetes. Behavioral changes. It causes sleep disturbances, insomnia, changes in appetite, eating too much or too little, hair loss, and decreased sex drive. It is true that thanks to the reptilian brain we survived as a species, but it is also true that life expectancy then was not very long, around 20 to 25 years. Currently we have another system called the neocortex or cerebral cortex, which, unlike the limbic system, which is impulsive and automatic, controls our emotions and is responsible for our logical, rational, and thoughtful thinking. It is true that they are not independent of each other and that they almost always act together. The key is to learn to use them correctly and not let ourselves be carried away by our instincts as if we were still in caves. The tools are there, you just have to use them.