Wikipedia Deep Dive

Hedonic treadmill

12 min read

Here's a puzzle that should trouble anyone who's ever wanted anything: lottery winners, within a year or two, are about as happy as they were before they won. And people who become paralyzed? After the initial shock, they report being happier than unhappy—and expect to feel about as good as everyone else in a few years.

This isn't optimistic speculation. It's what researchers found when they actually went out and asked people.

The phenomenon has a name: the hedonic treadmill. Like a treadmill at the gym, you can run as fast as you want, but you end up in the same place. Get a raise, buy a bigger house, land your dream job—give it a few months, and your baseline happiness creeps back to wherever it was before. The technical term is hedonic adaptation, and it might be one of the most important facts about human psychology that most people never learn.

The Discovery

The phrase "hedonic treadmill" first appeared in 1971, coined by psychologists Philip Brickman and Donald Campbell in a paper with the delightfully ambitious title "Hedonic Relativism and Planning the Good Society." Their argument was counterintuitive: no matter what happens to us, good or bad, we tend to return to a relatively stable level of happiness.

Seven years later, Brickman and his colleagues conducted the landmark study that would make this idea famous. They tracked down twenty-two lottery winners and twenty-nine people who had become paraplegic through accidents. They also interviewed a control group of ordinary people for comparison.

The results were startling.

Lottery winners reported being about as happy as they had been before winning. They expected to feel about the same in the future. The money hadn't fundamentally changed their experience of life.

The paraplegics, meanwhile, did report lower current happiness than before their accidents. But here's the thing: they still rated themselves above the midpoint on the happiness scale. They were more happy than unhappy. And when asked about the future? They expected to feel about as good as everyone else.

Something in the human mind was acting like a thermostat, constantly adjusting back toward a set temperature.

How the Treadmill Works

The treadmill isn't just one mechanism—it's several working together. Psychologists Shane Frederick and George Loewenstein identified three main processes that keep us running in place.

The first is shifting adaptation levels. Think of it like this: when you move from a quiet town to a noisy city, at first the traffic is overwhelming. Then something shifts. The noise becomes neutral—it's just the background. You've recalibrated what "normal" sounds like. The same thing happens with income. A raise feels fantastic at first. Then it becomes your new baseline, and you start wondering when the next one is coming.

But you don't become completely numb. If someone gave you a holiday bonus on top of that raise, you'd still feel pleased. You've shifted what counts as neutral, but you can still detect changes from that new normal.

The second process is desensitization—a genuine reduction in how strongly you respond to things. People who live in war zones for extended periods don't just get used to the violence; they actually react less intensely to destruction and loss that would have devastated them before. The emotional volume gets turned down.

The third process runs in the opposite direction: sensitization. Sometimes repeated exposure makes you more responsive, not less. Wine connoisseurs don't get bored with wine—they become more attuned to subtle differences that novices can't detect. Each sip carries more information, more pleasure, more meaning. This is the treadmill working in reverse.

Not Everyone Returns to the Same Place

The original treadmill theory suggested something almost mathematical: everyone has a neutral set point, and we all return to it after life's ups and downs. It was elegant. It was also wrong—or at least incomplete.

In 2006, psychologists Ed Diener, Richard Lucas, and Christie Scollon published a major revision. After reviewing decades of research, they concluded that the picture was more complicated and more interesting.

First, people aren't hedonically neutral. Some people are constitutionally sunnier than others. These set points differ from person to person, and they're at least partially inherited. Studies of twins suggest that roughly half of our baseline happiness level is genetic—built into our neurological wiring before we ever encounter the world.

Second, people might have multiple set points, not just one. Your overall life satisfaction, your day-to-day mood, your sense of meaning—these may each have their own baseline, and they can move somewhat independently.

Third, and most importantly: set points can change.

A German study followed over three thousand people for seventeen years, checking in annually to measure their life satisfaction. Most people stayed remarkably stable—their happiness fluctuated within a narrow band. But about a quarter of participants showed genuine shifts in their baseline over time. Nine percent experienced dramatic changes.

The treadmill, it turns out, has adjustable settings.

What Actually Moves the Set Point

If some life events can permanently shift our baseline happiness, which ones? Researchers have spent decades trying to answer this question, and the findings are humbling.

Marriage provides a boost—but most people adapt back to their original set point within a couple of years. The honeymoon period is literally that: a period. Having a first child follows a similar pattern. The joy (and exhaustion) is real, but temporary in terms of affecting your baseline.

Divorce causes a dip, but people tend to recover. Losing a spouse is harder—the research suggests slower and less complete adaptation. Losing a job hits men and women differently; women tend to bounce back to baseline, while men often don't fully return.

But here's where it gets concerning: some negative events seem to permanently lower the set point. Severe, long-term disability can shift baseline happiness downward in ways that don't fully reverse. Chronic unemployment appears to leave a lasting mark.

The pattern isn't symmetric. We seem better at adapting to good things than to bad ones. The treadmill runs faster in some directions than others.

The Biology Underneath

What's actually happening in the brain when we adapt to pleasure or pain?

Part of the answer involves a small seahorse-shaped structure called the hippocampus. This brain region is involved in memory, mood, and setting emotional baselines. A smaller hippocampus has been linked to depression and dysthymia—a chronic low-grade depression that colors everything gray. Certain activities and environmental factors can actually grow the hippocampus and, potentially, reset hedonic set points.

The amygdala matters too. This almond-shaped structure processes fear and emotional responses. Research in mice has found that resilience to suffering—the ability to bounce back from traumatic experiences—correlates with reduced fear responses in the amygdala and higher levels of a protein called brain-derived neurotrophic factor, or BDNF. One study even found that changing a single gene could make mice more resilient to depressing situations, like being forced to swim until exhausted.

This isn't just academic. Understanding these mechanisms could eventually help people with anxiety, post-traumatic stress disorder, and depression—conditions where the treadmill seems stuck in a bad place.

Prison, Trauma, and the Limits of Adaptation

How far does adaptation extend? Can people adjust to anything?

Researchers have studied prisoners, and the findings are what you might expect: being incarcerated lowers your baseline happiness. Your hedonic thermostat resets to a colder temperature. The more interesting finding is what happens after release: people tend to bounce back to their pre-prison levels. The experience leaves psychological marks, but the set point itself appears reversible.

Trauma victims show similar patterns. One study followed people who had sustained severe spinal cord injuries, checking in weekly for two months. A week after the accident, victims experienced far more negative emotions than positive ones—as anyone would expect. But by the eighth week, positive emotions had overtaken negative ones. The recovery wasn't complete, but it was real and remarkably fast.

There seem to be limits, though. Some events resist adaptation. Chronic pain, persistent unemployment, living in severe poverty—these appear to drag on happiness in ways that don't fully resolve. The treadmill has guardrails, and some circumstances push us against them permanently.

The Genetics Question

How much of your happiness is predetermined?

One famous study followed over a thousand pairs of twins for ten years. By comparing identical twins (who share all their genes) with fraternal twins (who share about half), researchers could estimate how much of the variation in happiness comes from genetic factors.

The headline number: about fifty percent.

Half of the difference between a naturally cheerful person and a naturally melancholic one appears to be written into their DNA before they're born. The other half comes from life circumstances and choices—but that's still a lot of genetic destiny.

Or is it? Some researchers have pushed back on these findings. Identical twins raised apart aren't necessarily raised in truly different environments. Similar-looking people get similar reactions from the world. Beautiful twins might both become accustomed to admiration; intelligent twins might both find school easy. The environment responds to the genetics, making it hard to separate the two.

The debate continues, but even the skeptics acknowledge that personality traits—neuroticism, extraversion, openness to experience—powerfully shape how we perceive and respond to life events. And those traits are at least partially heritable.

Practical Implications

If the hedonic treadmill is real, what does it mean for how we should live?

One clinical psychologist, Sonja Lyubomirsky, has developed therapeutic approaches based on these ideas. If we know that people have happiness set points, and we know that life events temporarily knock them off those set points, then therapy can focus on speeding the return to baseline after negative events.

More ambitiously, some research suggests the set point itself might be adjustable. Acts of kindness, for example, seem to provide lasting well-being benefits that don't fully fade. Helping others might be a way to ratchet the thermostat upward, one small act at a time.

Understanding hedonic adaptation also matters for resilience—the ability to withstand adversity without breaking. Psychologists have identified factors that help: secure relationships, positive self-image, emotional regulation skills, connections to community organizations, and an optimistic outlook. These aren't just nice-to-haves; they're the machinery that keeps the treadmill functional when life tries to throw you off.

The Transhumanist Dream

Some thinkers want to smash the treadmill entirely.

Transhumanist philosophers like David Pearce and Mark Alan Walker argue that future technologies could overcome hedonic adaptation altogether. Walker coined the term "biohappiness" to describe directly manipulating the biological roots of happiness. Pearce goes further, arguing that suffering itself could eventually be eradicated from the world entirely. He even suggests the last unpleasant experience in human history could be a precisely dateable event.

How might this work? A few possibilities have been proposed.

Wireheading—direct electrical stimulation of the brain's pleasure centers—could produce uniform bliss. But this approach undermines motivation and arguably defeats the purpose of being alive. Why would you do anything if you felt perfect regardless?

Designer drugs might offer sustainable well-being without the side effects of current pharmaceuticals. But a lifetime of pharmacological intervention seems impractical and raises obvious concerns about dependency and authenticity.

The most serious proposal involves genetic engineering. Some people are born with a condition called hyperthymia—a naturally elevated mood that stays high without the instability of mania. If we could identify the genes responsible and introduce them more broadly, we might be able to raise the entire species' hedonic set point. People would still respond to stimuli, still feel pleasure and pain in appropriate contexts, but their baseline would sit higher on the happiness scale.

Whether this is desirable, ethical, or safe is another question entirely.

Drugs and the Treadmill

There's a darker side to hedonic adaptation: addiction.

Researchers studying cocaine use in rats found that the drug didn't just provide temporary pleasure—it seemed to permanently alter the animals' hedonic set points. After exposure to cocaine, rats needed more of the substance to feel the same level of pleasure. Their baseline had shifted, and not in a good direction.

This is the treadmill weaponized against itself. Normally, adaptation protects us by keeping us relatively stable despite life's fluctuations. But addictive substances hijack the machinery. The brain adapts to the drug, requiring more and more to feel normal—not even to feel good, just to feel okay. The set point has moved, and now being sober feels like being in a hole.

This neurochemical adaptation helps explain why addiction is so difficult to treat. It's not just about willpower or wanting the drug. The brain has been physically recalibrated. Recovery isn't just stopping a behavior; it's waiting for the set point to gradually return to its original position—if it ever fully does.

What the Treadmill Teaches Us

The hedonic treadmill is often presented as depressing news. Why bother striving for anything if you'll just adapt back to where you started?

But there's another way to see it.

The treadmill is a form of resilience built into our psychology. It's why lottery winners don't become permanently insufferable and why accident victims don't despair forever. It's a stabilizing force that keeps us functional across a wide range of circumstances.

It also explains something important about the relationship between money and happiness. Beyond a certain point—enough to meet basic needs, avoid chronic stress, and have some security—more money doesn't make people much happier. We adapt. The mansion becomes normal. The luxury car becomes just a car.

This doesn't mean money doesn't matter at all. Poverty genuinely hurts, and the stress of financial insecurity takes a real toll. But the relationship between income and happiness flattens out much faster than most people expect. Understanding this might save years of chasing something that won't deliver what we hope.

Perhaps the most useful insight is this: since we adapt to good things quickly, lasting happiness might depend less on achieving particular goals and more on the journey itself. The activities that resist adaptation—close relationships, meaningful work, helping others, continued learning—tend to be processes rather than destinations.

The treadmill keeps running. The question is what you do while you're on it.