Imagine you have just won the lottery. One million euros. You jump for joy, call your family, and barely sleep because the excitement is so intense. For a few weeks, life seems radically different — lighter, brighter.

One year later? Studies suggest you will probably be just as happy — or unhappy — as you were before. No more, no less.

Welcome to hedonic adaptation: one of the best-documented phenomena in human psychology, and one of the most unsettling to face honestly.

The study that changed everything

In 1978, psychologists Philip Brickman, Dan Coates and Ronnie Janoff-Bulman published a study that became famous under the title Lottery Winners and Accident Victims: Is Happiness Relative?. Their protocol was simple but elegant: they interviewed three groups of people — lottery winners, people who had become paraplegic or quadriplegic after an accident, and a control group.

The results surprised everyone. Lottery winners were not significantly happier than the control group one year after collecting their winnings. Even more troubling: accident victims rated their everyday activities as more enjoyable than the winners rated theirs. Happiness did not seem proportional to the objective circumstances of life.

The conclusion was counterintuitive: we adapt. To almost everything. And much faster than we think.

What “adapting” really means

Hedonic adaptation refers to our natural tendency to return to a stable level of well-being — called the set point — after a positive or negative event, however significant it may be. This point varies from one person to another, but for each of us, it remains surprisingly constant over time.

In simple terms: you buy a new car, move into a larger apartment, or get the promotion you had been waiting for for months. For a while, you are happier. Then, almost imperceptibly, your level of satisfaction returns. Your expectations adjust. What was exceptional becomes ordinary. And you go back to your baseline.

We want what we do not have, until we have it.

This is the principle of the hedonic treadmill, a term coined by Brickman and Campbell as early as 1971: running faster and faster only to stay in the same place.

Why our brain does this

From an evolutionary perspective, hedonic adaptation makes sense. A human being constantly overwhelmed by wonder at a new cave would be too distracted to hunt. A human being unable to move beyond the pain of grief would remain paralyzed indefinitely. The brain therefore recalibrates pleasure and pain to keep us functional in a changing environment.

The problem is that this adaptation mechanism does not distinguish between what truly matters and what is superficial. It applies just as readily to higher income, a new relationship, moving to the city of your dreams, or material acquisitions. The brain optimizes for survival, not lasting satisfaction.

50%, 10%, 40%

In 2005, psychologist Sonja Lyubomirsky, together with her colleagues Kennon Sheldon and David Schkade, proposed a model that left a major mark on positive psychology. According to their analysis of the existing literature, our level of happiness is determined by three factors:

• 50% is genetic — your starting hedonic set point, partly inherited from your parents.
• 10% depends on life circumstances — income, social status, place of residence, objective health.
• 40% depends on our intentional activities — what we do, how we think, and the deliberate efforts we make to cultivate well-being.

This figure of 10% for circumstances is often the hardest data point to swallow. Our entire consumer culture rests on the opposite idea: that changing our circumstances — buying, traveling, acquiring, moving up socially — will make us lastingly happier. Yet this is structurally false, or at least greatly exaggerated.

It should be noted that this model has since been refined and qualified, particularly by Lyubomirsky herself. The boundary between the genetic 50% and the intentional 40% is not as clear-cut as a diagram might suggest. But the central idea remains robust: circumstances matter far less than we think.

Can we resist adaptation?

The good news is that hedonic adaptation is not completely airtight. Research suggests several concrete ways to slow its effect:

• Variety: varied experiences adapt more slowly than repetitive ones. A house remains a house, but a series of new experiences keeps renewing itself.
• Savoring: deliberately pausing to appreciate a positive moment delays adaptation. If paying attention is enough, it is because attention truly carries part of the experience.
• Active gratitude: remembering why something has value counterbalances the tendency to take it for granted. Not as a mystical exercise, but as cognitive recalibration.
• Relationships: high-quality social bonds are among the elements that best resist adaptation. We get used to an apartment, but a deep friendship can remain a lasting source of well-being — provided we maintain it.

What this changes in practice

Understanding hedonic adaptation does not make life sad — provided we draw the right conclusions from it. It teaches us that pursuing happiness through accumulation or changing circumstances is structurally bound to run out of steam. This is not a character flaw: it is a feature of human cognitive architecture.

What it frees up, however, is attention toward what better resists this erosion: how we spend our time, the relationships we cultivate, and the meaning we give to what we do. These things are less glamorous to promote — nobody advertises spending quality time with friends — and that is precisely why they are so often underestimated.

We keep running on the treadmill. But at least now, we know it is a treadmill.