I don’t often look to engineering for insights into mental health, but this week’s column is an exception.

Some readers may recall the 1986 Challenger space shuttle disaster, when the US shuttle disintegrated shortly after launch, killing its seven-person crew. In the aftermath of the disaster, Nasa asked sociologist Diane Vaughan to investigate what went wrong. The explosion was not the result of one terrible mistake, she concluded, but of a long process Vaughan called the normalisation of deviance. Engineers had gradually become accustomed to minor safety breaches because earlier launches had succeeded. The definition of “safe” had slowly changed over time, because deviant practices had become so familiar they no longer registered as deviant at all. It was basically a case of “Oh, that’s nothing” until the small issues built up and caused disaster.

Vaughan’s idea resonated beyond space travel, and experts in medicine, aviation and business schools have all borrowed her insight to understand how standards can drift without anyone noticing. With complex systems, there is always a risk that small departures from best practice are tolerated or ignored because nothing immediately goes wrong. Over time, what once would have triggered concern becomes routine, and minor breaches quietly lose their status as problems. Something similar can happen in ordinary life, with this same kind of normalisation showing up in various mental health problems, burnout, and lives that slowly become less satisfying. It rarely comes down to one big “mistake”. More often, things change bit by bit, as what feels “normal” slowly shifts over time.

Poor sleep, constant tiredness, self-criticism, and low-level anxiety can all come to feel normal. “That’s just the way things are”, “It’s just how I am” – the absence of abrupt crisis means we may not notice the slow damage. To give a more striking example, in some relationships, repeated abuse – verbal, emotional, or physical – can become accepted over time, again showing how deviance can slip into what feels normal. The same is true of relationships characterised by coercive control, where patterns of monitoring, restriction, or intimidation are gradually absorbed into everyday life.

It’s a bit like gradual hearing loss: because it happens slowly, people often don’t notice what they’ve lost until they struggle to follow a conversation or hear everyday sounds. Change often happens so slowly that it barely registers. As a result, over time, personal situations can shift far beyond what once felt right.

Adapting

It makes sense when you think about it. As humans, we’re good at adapting. Sudden pain or loss grabs our attention, but slow and small changes often pass us by. As long as work gets done, bills are paid, and relationships continue, we tend to assume everything is “fine”, “normal”. When burnout or overwhelm or depression finally arrive, it might feel like it came out of nowhere. Most of the time, though, it has been creeping up slowly, through small changes and compromises that may not have seemed worth noticing. Such patterns sometimes become more obvious in midlife. Some people begin to feel that they are functioning on the outside but feeling increasingly flat inside. There may be no crisis or obvious loss, just a sense that life doesn’t feel nearly as full as it once did. The irony is that this often happens because someone may be good at coping and getting on with things. The better we are at managing, with keeping the show on the road, the easier it is to overlook slow and unwelcome changes. It’s a bit like a backpack that slowly gets heavier. At first, it barely matters, but over time the weight starts to wear you down. The danger is that eventually life may feel the same, with small compromises and lost pleasures adding up until things become hard to manage.

Now, this is not to imply that we should all monitor ourselves anxiously or treat ordinary discomfort as unacceptable. After all, some discomfort and dissatisfaction is simply part of life, and it would be unwise to pretend otherwise or to expect every day to be all milk and honey. However, living well means stopping now and then to check what we have come to accept, instead of always running on autopilot. It’s worth asking: if I were starting over, would I still choose to live the way I’m living? When did XYZ become normal? What am I tolerating just because I’ve adapted? What small changes could make a difference?

Noticing the drift is often the first step to living better.

Linda Hamilton is a Kinsale-based cognitive behavioural therapist. If you would like to get in touch with her, call 086-3300807 For more information, go to www.kinsalecbt.com