All of this is pretty grim news. In the face of repeated stressors, we may be able to precariously retain the state of allostasis, but it does not come cheap and the efforts to reestablish the balance will eventually wear us down.
An interesting model/analogy used in stress literature is that of ‘two elephants on a seesaw’. Here is a way to think about it: put two small children on a seesaw and they can pretty readily balance themselves on it. This represents that state of the body in allostasis when nothing stressful is going on and the children represent the low levels of stress hormones in the body. In contrast, the torrents of hormones in response to severe stress can be thought of as two massive elephants on the seesaw. Sure, they can balance but with great difficulty. Repeatedly getting the two elephants to balance can lead to problems—
• First, enormous potential energy is required to maintain the balance. That energy is wasted instead of being put to more useful tasks like growth in the body. This is equivalent to diverting funds from long-term projects for short-term emergency management. Obviously, a wasteful way to manage your finances.
• Extending our analogy further, the mere presence of two elephants is damaging. The elephants trample over everything in their way; they leave a lot of mess behind them and by their sheer weight wear out the seesaw. This is a crucial point—it is hard to fix one major problem in the body without knocking something else out of balance. You may be able to solve one problem using the elephants (massive stress hormones) but you will certainly damage some other area.
• A final subtle point, once the two elephants are balanced on the seesaw it is very difficult for them to get off. Either one jumps off and the other comes crashing down or their actions are coordinated which is an extremely delicate task. This reveals that stress-related diseases can arise from turning off the stress responses too slowly, or turning off different components at different speeds.
Another way to look at it is to visualize two tug-of-war teams skillfully supporting their rope with a minimum of tension; the body works to carefully maintain metabolic equilibrium by making adjustments whenever something disturbs this balance. The strong men in these teams are hormones. The trouble is that some stress-response hormones don’t know when to quit pulling. They remain active in the brain for too long and end up causing problems all around.
The punch line of the preceding discussion on stress response is that if you repeatedly turn on the stress response or cannot turn it off at the end of the stressful event, the response can become as damaging as some stressors themselves. A large percentage of what we think of when we talk of stress-related diseases are disorders of excessive stress response. It is actually more accurate to say that chronic stressors can potentially cause diseases that will make you sick.
If you already have such a disease, stress increases the risk of your defenses being overwhelmed by the disease. This may sound like nitpicking but is very important from the point of designing ways to intervene and prevent stress-related diseases. Think about it for a moment: The more steps that we put between the stressor and the disease, the more are the places for intervention and prevention of damage.