Why smelling a pine tree can instantly lift your mood

Pine is one of those scents that can change a room, and your mood, in an instant. One whiff, and suddenly you’re transported to a world of woodsy snowscapes, twinkling lights, a fresh-cut tree shedding needles in your childhood living room. The scent feels soothing and joyful…but why? Turns out the answer has less to do with what’s inside the tree, and everything to do with what’s inside us. 

“There is nothing that is in pine that has any specific, inherent pharmacological influence at all on humans,” says Dr. Rachel Herz, a neuroscientist at Brown University and an expert on the psychological science of smell.

“The way it works is through learned associations. If I have associated the smell of pine with relaxation, then it’s going to relax me. If, for whatever reason, I associate pine with anxiety, that’s how it’s going to affect me. If I have never smelled pine before, and have no clue as to anything about it, there’s going to be no effect.”

Aromatherapy works, but not the way it’s advertised

Pine contains compounds called terpenes, like α-pinene and limonene, which are touted in wellness circles for their stress-reducing and mood-boosting properties. Aromatherapy brands frequently promote pine essential oils with terms like “refreshing” and “uplifting,” suggesting there’s something inherently calming in the chemistry of the tree itself.

But that idea doesn’t hold up scientifically, according to Herz. She says the perception of scent occurs in the amygdala-hippocampal complex, otherwise known as the primary olfactory cortex. It is this mechanism that drives pleasant experiences around particular scents. 

“What I always like to say is that aromatherapy works, but not in the way people think it does,” she says. “If I have an emotional association around a certain smell, that’s going to be instantly activated upon smelling a particular scent. It’s actually more immediate than if there was a drug-like mechanism that would take time to metabolize.”

She added that a person would not need to consciously think about their pleasant associations with pine to experience the uplifting feelings. “You could consciously experience that nostalgia, but what’s going to happen first is you’re going to have that mood boost, and that happy feeling,” she says. “Then you might reflect on a memory of a time you went camping as a child, for example, but that is not necessary.”

Humans, Herz explains, are “generalists,” meaning we can thrive in many different environments. Unlike species that are born knowing exactly what certain smells mean (like which scent signals a predator or poison), humans have to learn what a smell signifies. 

“It wouldn’t make sense for us to gravitate toward pine smell willy-nilly,” she says. “In certain circumstances, it could actually signify danger.”

For example, if a person’s first whiff of pine occurs while being chased through the woods by a ravenous coyote, the scent is unlikely to awaken a cozy vibe later on.

Festive wreath vs. floor cleaner: the importance of context in pine smells

Sure, you might experience a happiness spike when you take an invigorating hike through the forest, or hang a holiday wreath on your front door. But what about when you’re using pine-scented cleaning products to scrub the bathroom, or hanging one of those pine tree air fresheners to mitigate a friend’s chain-smoking in your car? Does it make a difference?

It depends on your overall perception of the experience, Herz says. “Let’s say you have an essential oil, or a real tree or a chemical fabricated for a cleaning product. If a person is blindfolded and smells each of these samples, the perceptual experience would be the same,” she says. “Where context really comes into play is in the interpretation. If I’m standing in the bathroom opening a bottle of pine cleaner to clean the toilet, that pine smell is going to have a completely different connotation for me.”

In fact, Herz and colleagues conducted a study in which they presented a mixture of two chemicals to participants. The chemicals were placed in identical white jars with black lids, and consisted of pellets underneath cotton. Participants unscrewed the lids and sniffed the cotton.

In one instance, Herz said she handed the participants the jar and told them they were smelling parmesan cheese. She then asked a series of questions about the smell and the feelings it evoked. 

“They would say it was very pleasant, very familiar, and that they would eat it,” Herz says.

A week later, when the participants came back to do the study again, Herz presented the jar containing the same scent—only this time, she told them they were smelling vomit.

“People were saying, ‘Oh that is disgusting,’ and ‘I would never eat that,’” she says. “They could not believe me when I told them it was the exact same scent. It’s like doing a magic trick.”

Herz maintains that although pine scent might not have inherent mood-boosting compounds, its effects on well-being should not be dismissed.

“It’s not pharmacology: It’s psychology,” she says. “But emotions are real, and they have real physiological consequences.”

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