Why Stress Is Bad For You
Why Your Stress Is Killing You
How Cortisol Works And Why Stress Can Be Bad For You
It’s easy to envy your dog when life gets tough, but don’t fool yourself: every single creature on Earth experiences stress. Scientists have compared the molecules and stress response among different species and there is a surprising degree of similarity. All animals have the ability to make proopiomelanocortin (POMC), a large molecule that is so important that it has been conserved in the genetic code of every living thing that has evolved since our slug grandpa.
Proopiomelanocortin is the parent molecule to a wide variety of peptides, including adrenocorticotropic hormone (ACTH), which travels to the adrenal glands and stimulates the release of the hormone cortisol. Many are familiar with cortisol as being a stress hormone, and it is a molecule that has been around for hundreds of millions of years. Over time, different tissues evolved to specialize their responses to cortisol.
That’s how Mother Nature works – it’s easier to have a single molecule perform a variety of jobs rather than having to find individual specialists. It’s interesting to note that POMC is also the parent of endorphins, the hormones that give us pleasure and relief from pain. The difference between suffering and pleasure therefore, is a matter of how the signal is perceived by the brain.
Cortisol evolved to get us into action, irrespective of whether it’s for prevention or promotion. When early life emerged from the darkness of the deep oceans, it immediately had to contend with the cyclical patterns of day/night, and summer/spring/winter/autumn, and cortisol was the molecule of choice to handle the job. Cortisol plays a crucial role in the circadian rhythm of all animals.
In the morning, cortisol rises until it peaks at around 7:00am - 8:00 am, helping us get out of bed and feeling ready to “seize the day” (the fact that many of us don’t feel pumped in the morning is a testament to how out of sync we are with our natural circadian rhythm). Cortisol then gradually tapers off as the day wears on, reaching its lowest levels around 11:00 pm – 12:00 am.
As an action molecule, cortisol is an expert at providing energy. It stimulates gluconeogenesis - the synthesis of new glucose from protein, lactate, and fatty acid backbones (glycerol). It also stimulates glycogenolysis – the breakdown of starch-like carbs stored in your muscles and liver. To ensure that blood glucose levels stay high, cortisol inhibits the action of insulin, the hormone responsible for shuttling glucose into cells for storage.
Having plenty of sugar in the blood is a prerequisite for any type of action, like when you’re running away from a bear or fighting a croc. But it’s less than useful if you’re sitting traffic or simply living the day-to-day grind of balancing job, family and finances. The unused energy is eventually deposited back into your fat stores, but preferentially around your abdomen. Was evolution so flawed that it wasn’t able to know the difference between a tiger and a bad credit score? The truth is that it isn’t cortisol per se that’s the problem, but rather its regulation.