Cortisol (hydrocortisone, 17-OH-corticosterone) is produced by stress, and is a bad word these days. When I was a practicing allergist, Cortisol worked wonders with asthma, and as a salve helped my patients with eczema.

It functions in the body as a key part of the stress reaction, which preparers the animal body for “Fight or flight”. Cortisone raises the blood pressure, heart rate and blood sugar, and shuts down The immune system, which is not as necessary in times of emergency. It is this last function which helped my patients with asthma and eczema, which are diseases of excessive immune reactivity. You may have heard of the use of dexamethasone( A relative of cortisol ) in severe Covid, which is made worse by an excessive immune response.
Modern life is a pressure cooker, requiring continuous activity and deadlines. The blood Cortisone level, which is raised by stress, is helpful in the short term, but deleterious when persisting over the long term. The prolonged elevation of blood Pressure, blood sugar and heart rate, coupled with a decrease in bone and collagen formation can lead to all kinds of problems including weight gain, diabetes, cardiovascular problems, osteoporosis and mental decline.
Although cortisol in the short term can enhance memory (think of flash – bulb memory), in the long run it decreases hippocampal function, impacting memory.
For these and other reasons, Modern Life makes it desirable to reduce stress and the accompanying elevation of cortisol . Our old friends, Proper sleep, diet and exercise are critical, and help activities such as laughter and yoga to reduce stress. The following reference will cover this in more detail.