From a biological perspective, we suffer because of the consequences of the stress response, not because of the stressors. In its normal state, the body has some mechanisms to protect itself from the damages of the stress response. Cortisol—despite its bad reputation— is one of them. Cortisol, in fact, controls the duration and the intensity of immune system activation in response to a stressor and pulls the system back to a non-inflammatory state when the reaction is over. This is extremely important since inflammation is a crucial risk factor for all chronic diseases.

Unfortunately, the modern usage of the stress apparatus ruins the very mechanisms that should protect us from the bodily damages of stress. This causes an increased vulnerability for a general state of inflammation and, therefore, for a large spectrum of disorders.

It would be easy to think that the stress response is too ‘sensitive’ and that it should be able to better cope with our current way of living. However, there is a reason for our biology’s apparent inability to keep up with modern stress: The stress response evolved in an environment where the stressors were physical, and the activation of the stress system yielded the perfect advantage and adaptation to preserve life.  The response, in fact, doesn’t have the goal to protect the body, but to protect the survival of the organism, which is a radically different thing. 

The stress response protects life but can damage the body. 

In response to a threat, the body undergoes a series of changes that can cause tissue damage and altered immune function. In a general way, the changes caused by the stress response alter the biological feedback and the physiological regulation of bodily systems.

For this reason, those changes were meant to occur only when the benefits outweighed the costs—for instance, in the presence of a real physical threat.

In the Western world, we no longer have physical stressors. On the other side, psychological and social stressors have increased. Thoughts and worries about present and future stability, as well as tensions in the family and at work, are our main sources of stressors. In addition, memories and old feelings are enough to activate the stress response.

Even the mere anticipation of a difficulty is stressful for the mind and the body. This happens because the brain doesn’t tell the difference between what is really happening at a given moment and what is just a possibility entertained in our minds.

Anytime the brain receives a signal of danger (real or imagined), it prepares you to fight: better safe than sorry.

The anticipatory nature of the brain makes sense if we consider its evolutionary advantage. The anticipation of danger is in fact linked to the anticipation of what the body is going to need in a short future. This allows the brain to induce changes in the body to fulfill those needs before they arise. The goal is to maximize survival. The process is quite smart.

However, there is a difference between present and anticipated physical danger and real or imagined psychological danger. A physical threat, sooner or later, is over—either because we face it, or because we realize it was a false alarm and we allow ourselves to relax.  Psychological stressors, in contrast, can go on virtually forever, with no containment. Above all, bodily changes follow our psychology and go on with no containment either. They are never properly resolved, because the only way for them to be over is for the brain to stop signaling a danger. In other words, the body remains in a stressed-out state, and this puts our health at risk.

Biologically speaking, the stress response is a physical reaction to a physical danger. It didn’t change as we shifted from physical to social and mental threats.

Today, we have psychosocial stressors that we don’t physically fight. Yet, the stress response remains a physical reaction. One may wonder why the response didn’t change along with its causes, as would appear logical. 

However, we must consider an important feature of evolution: Structures and functions are repurposed to serve new adaptations. There wasn’t the need for a new stress system, because the pre-existing one was already good enough to cope with temporary mental stressors as well.

Physical changes in response to transient emotional stressors are not damaging in the short term. In other words, temporary emotional stress doesn’t hijack the protective mechanisms of the stress response. Therefore, when the psychosocial stress is limited, the body is still capable of counteracting potential side effects.

Moreover, there is another interesting reason that the response didn’t change to cope with psychological stress. The stress response, which evolved to face physical dangers, induces brain and mood changes, too. Those changes are also beneficial when the challenge is merely psychological. One example is the tendency of our ancestors to retire while they were healing wounds or infections caused by a fight. The same changes happen today in case of depression, with the difference being that we are healing emotional wounds.

Therefore, looking at our biology, it seems clear that the problem is not depression. In fact, we are biologically equipped to cope with it; giving ourselves space and retiring for a while from social activities serves the purpose of enabling us to return to a more balanced state. The problem is chronic depression, when a balanced state seems to be lost forever.

Whatever becomes chronic makes any future adaptation very difficult because it adds an element of rigidity into the system that disrupts the regulation of the organism, which is, by definition, dynamic and ever-changing, just like the external world where the organism is supposed to live.

It almost seems that our biology is trying to send us a message: We are not created to be worried all the time. We are not meant to feel and think that we are always in danger or that our lives don’t make any sense.

Environmental and lifestyle factors disturb the stress system and make us weaker.

In addition to what discussed above, we must add environmental and lifestyle factors that contribute to never-ending pressure. 

Modern life interferes with natural biological rhythms in many ways. Going to bed too late, frequent traveling and jet lag, shift work, polluted environment, lack of exercise, eating the wrong food, smoking, drinking: all are examples of current lifestyle habits that have the power to alter the body’s ability to counteract the negative consequences of the stress response.

The social and physical environment has a gradual and cumulative negative effect on our physical and mental inner balance. This makes us weaker when it’s time for us to gather our resources and cope with a difficult event.

In conclusion, we are more easily stressed out because too much physical and mental energy is used just to stay alive, while at the same time we seem to have lost the ability to replenish our resources.