—Photo-illustration by TIME (Source: Jolica via Canva)
Whoever first suggested stopping to smell the roses was on to something. But there’s a catch: Not all roses smell good to all people. Our response to scent is deeply personal, shaped by memory, culture, and even genetics.
What matters more is figuring out which smells resonate with you—and then giving yourself enough time to experience them. “Deliberately sniffing something is almost like an act of mini protest,” says Kate McLean-MacKenzie, a designer and researcher at the University of Kent in the U.K. who maps “smellscapes” across the globe. “It’s like, ‘I’m not going to just look at it. I’m actually going to bend down and sniff it.’ It’s not illegal, but people will look at you strangely.”
When you do—and when you hold that inhale for just 30 seconds—something measurable happens: Your heart rate slows, your nervous system shifts, and your mood lifts. Your brain, wired to respond to scent long before rational thought existed, starts doing exactly what it was built to do.
Here’s what researchers know about why.
Your brain on scent: why smell hits so deeply
Part of what makes scent so powerful is how differently the brain processes it compared to other senses.
“Mood change is one of the more common effects of smelling something,” says Pamela Dalton, a cognitive psychologist with the Monell Chemical Senses Center in Philadelphia, a nonprofit research institute dedicated to the study of taste and smell. “Olfaction has a more direct impact on emotion than any other sense. There’s no question about that.”
Here’s why: When you inhale, odor molecules bind to receptors in your nose and travel to the olfactory bulb at the front of the brain. Unlike touch, hearing, or vision—which all pass through a relay station called the thalamus before we consciously register them—smell skips that step entirely, connecting straight to the limbic system. That’s the brain’s emotional center, home to the amygdala and the hippocampus, where memories live.
It’s an architecture that explains why scent doesn’t just trigger feelings: It pulls up entire emotional landscapes. “When something is associated with a memory,” Dalton explains, “that scent becomes attached to that emotion and that experience, such that it brings back the same emotions you had in that moment—not just the memory, but also the emotional impact of it.” Think of your grandmother’s perfume, for example, or the wafting aroma of a favorite childhood meal.
Scent doesn’t just shape what we feel—it shapes how we breathe. Inhale something pleasant, and you naturally breathe more deeply, and that deeper breath slows the heart. Valentina Parma, senior director of multisector engagements at Monell, describes it as “the bottom-up, data-driven version of meditation.” The inverse is equally automatic: Encounter something aversive, and you instinctively pull shallower breaths, taking in less of the world.
That this system is so powerful is, in a sense, ancient news. Olfaction is among the oldest of our sensory systems: It evolved long before the cortex, the brain structure responsible for rational thought, ever developed. It wasn’t built to help us think. It was built to keep us alive: to orient us in space, flag danger, and draw us toward what sustains us. “It’s the oldest sensory system that could bring us information from a distance,” Dalton says. All of this evolution, she adds, “predisposes it to have this emotional impact when we smell something.”
Your nose doesn’t lie—but it does play favorites
The science of why scent is so personal traces back to the beginning of life. Certain compounds found in breast milk share chemical properties with vanilla—which may be why, across cultures and populations, vanilla registers as universally pleasant to almost everyone who encounters it. “We may be forming these associations at a very early age,” Dalton says, “and once these memories are formed, they’re very strong and robust.”
Culture layers on top of biology. Grow up in an environment where certain smells are woven into daily life—a particular spice, a flower that blooms every spring outside your window, a fragrance someone you loved always wore—and those associations become essentially permanent.
Even the most well-researched scents can’t override a lifetime of personal history, though. Lavender, for instance, appears in study after study as a reliably calming fragrance. But Parma, who’s spent her career studying olfaction, has a stress reaction to it. “Whenever I read these blanket statements about, ‘Oh, the odor of lavender will relax you no matter what’—that blanket statement is rarely true in olfaction,” she says. “We have a huge complexity at the level of biology, and then we have all of our experiences that are hard to account for,” which means no one can count on any one scent to affect them the same way it affects other people.
There’s also the matter of genetics. Parma points to a compound called androstenone: a steroid produced by pigs that researchers began studying in humans after noticing its pheromonal properties in animals. It turned out to be a remarkably clean illustration of how differently human noses can be wired. Roughly 30% of people smell it and detect something urine-like. Another 30% find it sweet, almost vanilla-like. The remaining 30% can’t smell it at all. Same molecule, same room, three completely different realities. “When we’re in the same room at the same time with the same bottle, we’re not even able to agree on what it smells like,” Parma says.
A smell walk can change how you experience the world
McLean-MacKenzie wanted to see what all that variability actually looks like when you get a group of people together to smell the same city. She’s led “smell walks” on five continents, collecting olfactory data from cities including Kyoto, Kolkata, Cartagena, Malmö, and New York. The premise is simple: a small group—anywhere from five to 20 people—walks a short route and pays attention to what they smell.
The walk unfolds in three stages. First up is what McLean-MacKenzie calls “smell catching”—the olfactory equivalent of chasing butterflies. “Wait for smells that are like butterflies on the wind,” she says, “and if they happen to fly past your nose, you’re going to catch them and scoop them up by inhaling deeply.” Participants write down not what they think they’re smelling, but what they’d name it—a distinction that unlocks something unexpected. One walker in Ojai, Calif., for example, caught a scent and called it “the smell of shattered dreams.” The source? Stale beer on a sidewalk, which sent her straight back to walking home alone on a Friday night at age 18.
The second stage is smell hunting: getting low, getting close, and engaging with the environment the way an animal would. Smell molecules are heavier than air, McLean-MacKenzie explains, so there are more of them near the ground. Participants pick things up, scrunch leaves, and lean into fences and park benches. One example of the kind of description that emerges when you actually stop and pay attention: “The warm smell of wood in the spring sun park bench.”
Then comes the surprise that stops almost everyone: the scentless flower. As McLean-MacKenzie describes it, it’s “the eternal disappointment of people smelling flowers and realizing there’s no scent.” It isn’t their imagination—in the multi-billion dollar floral industry, breeders have long prioritized vase life, durability, and visual appeal over fragrance, and some cultivated blooms have lost their scent as a result. “We value the visual over the scent,” McLean-MacKenzie says. “We’ve removed half of its restorative capacity.” (Her take on the situation? “Cruelty to flowers.”)
The third stage is smell exploration: Participants choose one category—park benches or, say, trash cans (yes, really). Then they smell four examples of it, describing each one without using the object’s name. The goal is to break the mental shorthand that keeps most of us from actually perceiving what’s around us. “Trash cans all smell different,” McLean-MacKenzie notes, “and half of them aren’t unpleasant—but everybody assumes they will be.”
At the end of the walk, the group reassembles and shares their experience. This, McLean-MacKenzie says, is the revelation at the heart of the whole exercise: that we have all been moving through the same world, perceiving it completely differently. “We get so used to not actually trusting our noses, or trusting ourselves,” she says. “To witness that space through other people’s noses is an incredible thing.”
From her smell walk data—she estimates she’s collected notes from 50 to 70 cities worldwide—one pattern holds almost everywhere: Floral scents rate a 6 or 7 on a 7-point scale of pleasantness. “There’s no such cohesion in any other category,” she says, though naturally there are always a few exceptions. One Montreal walker, for example, described “the intoxicating hyacinth” and assigned it a 3 out of 7. “The sickening intoxication,” they wrote. Too much of a good thing, McLean-MacKenzie explains, and the pleasure tips into overwhelm. Then there’s her personal favorite data point: a smell note from one walker, rated a perfect 7, that was simply labeled “smells like childhood and catching butterflies.”
The best way to tap into scent
You don’t need to join a smell walk to start paying attention. You just need 30 seconds and a patch of grass, a backyard, or even a single potted plant on a windowsill.
The science backs that up. When you inhale intentionally and deeply, you significantly increase your chances of odor molecules reaching your olfactory receptors. And that deep breath does something else: It activates the parasympathetic nervous system—the body’s rest-and-digest mode—slowing the heart and quieting the mind.
The difference between a passing sniff and an intentional one turns out to matter enormously. “Spend at least 30 seconds actually calming your system down and really inhaling and thinking about it,” McLean-MacKenzie advises. “It’s not a long time, but it’s possibly more time than most people give it.” A quick sniff as you rush past a rosebush is a completely different physiological event than stopping, leaning in, and breathing. A few ways to start:
Try smell catching on your own block. You don’t need a curated route—just walk slowly and wait for scents to come to you. Inhale deeply when something catches your attention. Write down what you’d name it, not what you think it is, McLean-MacKenzie suggests.
Rotate your scents by mood. Broadly speaking, sweet, powdery floral scents—think lavender and rose—tend toward relaxation and a calmer mood. Citrus, pine, mint, and other sharp or cooling scents tend to be more energizing, Dalton says, partly through the trigeminal nerve, which registers sensation as well as smell. “That can shift your mood because it’s part of the touch system in your body, but it happens to be in your nose,” she says. “So when you smell something strong enough, it will activate both the smell system but also this other touch system, and that sensation can be arousing.”
Don’t overthink it. A smell walk is meant to be “an embodied, holistic experience,” McLean-MacKenzie says. “It’s about not trying to rationalize it all the time, but actually just responding.” Your associations are your own—what matters is that you notice them.
Pay attention to what changes. Smell is also a health signal: Shifts in how things smell to you, or a sudden loss of scent, can be early indicators of illness worth flagging to a doctor. “Losing one’s sense of smell makes you not able to enjoy aspects of life,” Parma notes. “This takes a bigger toll than people imagine.”
And if you need one more reason to bend down and sniff the daffodils: You can’t do it on a screen. “Digitally, you can’t transmit a smell,” McLean-MacKenzie says. “I just love it. It means you have to engage with the outside world to be able to get the best experience from it.”
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