In 1967, Thomas Holmes and Richard Rahe assessed thousands of medical patients and asked them about their life experiences, attempting to establish a link between stress and illness.11 They succeeded. This data led to the formation of the Holmes and Rahe Stress Scale, where certain events are assigned a certain number of “life change units” (LCU). The more LCU an event has, the more stressful it is. A person then says how many of the events on the scale happened to them in the previous year, and an overall score is assigned. The higher the score, the more likely someone is to become ill from stress. Top of the list is “death of a spouse” with 100 LCU. Personal injury scores 53, getting fired 47, trouble with in-laws 29, and so on. Surprisingly, divorce scores 73, whereas imprisonment scores 63. Oddly romantic, in a way.
Things not on the list can be worse again. A car crash, involvement in a violent crime, experiencing a major tragedy—these can cause “acute” stress, where a single incident causes intolerable levels of stress. The events are so unexpected and traumatizing that the usual stress response is, to quote Spinal Tap, “turned up to 11.” The physical consequences of the fight-or-flight response are maximized (you often see someone shaking uncontrollably after serious trauma), but it’s the effect on the brain that makes such extreme stress hard to get over. The flood of cortisol and adrenalin in the brain briefly enhances the memory system, producing “flashbulb” memories. It’s actually a useful evolved mechanism; when something severely stress-inducing happens, we definitely don’t want to experience it again, so the highly stressed brain encodes as vivid and detailed a memory of it as possible, so we won’t forget and blunder into it again. Makes sense, but in extremely stressful experiences it backfires; the memory’s so vivid, and remains so vivid, that the individual keeps re-experiencing it, as if it were constantly reoccurring.
You know when you look at something extremely bright and it lingers in your vision because it was so intense it’s “burned” onto your retinas? This is the memory equivalent of that. Except it doesn’t fade, it persists, because it’s a memory. That’s the point, and the memory is almost as traumatic as the original incident. The brain’s system for preventing reoccurrence of trauma causes reoccurrence of trauma.
The constant stress caused by vivid flashbacks often results in numbing or dissociation, where people become detached from others, from experiencing emotions, even from reality itself. This is seen as another brain defence mechanism. Life is too stressful? Fine, shut it out, go into “standby.” While effective in the short term, it’s not a good long-term strategy. It impairs all manner of cognitive and behavioral faculties. Post-Traumatic Stress Disorder (PTSD) is the most well-known consequence of this occurrence.12
Thankfully, most people won’t experience such major traumas. Consequently, stress has to be sneakier to incapacitate them. So there’s chronic stress, which is where you get one or more stressors that are more persistent than traumatic, so they affect you over the long term. A sick family member to care for, a tyrannical boss, a never-ending stream of deadlines, living on welfare and never clearing your debts, these are all chronic stressors.*
This is bad, because when too much stress occurs over a long period, your ability to compensate suffers. The fight-or-flight mechanism actually becomes a problem. After a stressful event it typically takes the body 20–60 minutes to return to normal levels, so stress is quite long-lasting as it is.14 The parasympathetic nervous system, which counteracts the fight-or-flight response once it’s no longer needed, has to work hard to undo the effects of stress. When chronic stressors keep pumping stress hormones into our system, the parasympathetic nervous system is exhausted, so the physical and mental consequences of stress become “normal.” Stress hormones are no longer regulated and used when needed; they persist, and the person becomes constantly sensitized, twitchy, tense and distractible as a result.
The fact that we can’t counteract stress internally means we seek external relief. Sadly, but predictably, this often makes things worse. This is known as the “stress cycle,” where attempts to alleviate stress actually cause more stress and consequences, which result in more attempts to reduce stress, which in turn cause more problems, and so on.
Say you get a new boss who assigns you more work than is reasonable. This would cause stress. But said boss is not open to reason or rational argument, so you work longer hours. You spend more time working and stressed, so you experience chronic stress. Soon you start consuming more junk food and alcohol to unwind. This negatively affects your health and mental state (junk food makes you unfit, alcohol is a depressant), which stresses you out further and makes you vulnerable to further stressors. So you get more stressed, and the cycle continues.
There are numerous ways to stop the ever-increasing stress (adjusting workloads, improved healthy lifestyle, therapeutic assistance, among others), but for many this just doesn’t happen. So everything builds up, until a threshold is crossed and the brain essentially surrenders; much like a circuit breaker will cut the power before a surge overloads the system, so ever-increasing stress (with associated health consequences) would be terribly damaging for brain and body, so the brain puts a stop to, essentially, everything. Many argue the brain induces a nervous breakdown to stop stress escalating to the point where lasting damage can occur.
The threshold between “stressed” and “too stressed” is hard to specify. There’s the diathesis-stress model, where diathesis means “vulnerability,” which describes how someone who is more vulnerable to stress requires less stress to push them over the edge, into a full breakdown where they experience a mental disorder or “episode” of some description. Some people are more susceptible: those with more difficult situations or lives; those already prone to paranoia or anxiety; even those with tremendous self-confidence can be brought low very quickly (if you’re very self-confident, losing control due to stress could undermine your whole sense of self, causing immense stress).
Exactly how a nervous breakdown plays out also varies. Some people have an underlying condition like (or predisposition to) depression or anxiety, and overly stressful events can bring this on. Dropping a textbook on your toe hurts; dropping it on an already-fractured toe hurts considerably more. For some, the stress causes their mood to plummet to a point where it’s incapacitating, and thus depression occurs. For others, the constant apprehension and persistence of stressful occurrences causes crippling anxiety or panic attacks. The cortisol released by stress is also known to have an effect on the dopamine systems of the brain,15 making them more active and more sensitive. Anomalous activity in the dopamine systems are believed to be the underlying cause of psychosis and hallucinations, and some nervous breakdowns do produce psychotic episodes.