How Are Different Smells Really Affecting Your Mood?

Ever wondered why you feel a surging warmth of nostalgia at any whiff of cotton candy, or a visceral anger at the odor of steaming Brussels sprouts, or why that one men’s cologne makes you suddenly so sad and forlorn?

The answer has a lot to do with mood, but maybe even more to do with memory. Rachel S. Herz, an assistant psychology professor at Brown University, told Scientific American about the effects memories, and the smells that trigger them, can have on our moods.

Instead of smells having immediate, drug-like impacts on us, Herz says that actually it’s us working on them through former experiences. “In order for an odor to elicit any sort of response in you, you have to first learn to associate it with some event,” she says.

Basically, you learn to associate some sort of feeling, whether positive or negative, with a specific event. Later, when you encounter a similar event or smell, the original emotional reaction is triggered. Ever notice how objectively sterile smells can cause anxiety in lots of people? Might have something to do with associated pain during hospital and doctor visits, where sterilized surfaces are the norm. Our experiences are filed away in our brain to be later linked with new experiences in what is known as associative learning.

This is especially true of olfactory interactions compared to the other senses because of the way our brains are wired. Herz explains this connection: “The olfactory bulbs are part of the limbic system and directly connect with limbic structures that process emotion (the amygdala) and associative learning (the hippocampus). No other sensory system has this type of intimate link with the neural areas of emotion and associative learning.”

So that overwhelming nostalgia over spun sugar? Probably has to do with all the happy autumn days you spent at the state fair as a kid. Anger over the veggies? Maybe there’s still some resentment over mom forcing down those Brussels every single week. Intense sadness brought on by the arguably pleasant smell of a stranger on the street? Could be the same cologne your old flame used to wear, and you just wish you could be friends already.

Whatever the reaction, technically, it’s all in your head.