If you suddenly hate your favorite fragrances, science says your stress levels could be to blame

There’s a reason why the wellness market is chock-full of lavender pillow sprays to help you fall asleep, and why so many of us keep bottles of peppermint essential oils on our desks to stay productive at work. The scent-brain connection is real, and legitimate research has shown that sniffing certain fragrances can have a major impact on your mood. But if your go-to calming scent concoction has suddenly stopped working, your stress levels could be to blame.

“Our sense of smell is intricately linked to our olfactory center of our brain—in fact our sense of smell is only one synaptic jump from our emotional brain which controls our stress response,” says Amy Galper, co-founder of the New York Institute of Aromatic Studies. To get super science-y for a second, your sense of smell (or “olfactory neuroanatomy”) is intertwined with the parts of your brain that control your emotions, including  the amygdala, hippocampus, and orbitofrontal cortex. When you sniff something, it has to get through all of these areas before it gets to the part of your brain that’s able to process the scent, which is why we often have such strong associations between fragrance and emotions. (Can you smell Axe Body Spray without thinking of your high school boyfriend? Because I cannot.)

“Because of this, aromas can trigger emotional and subsequent physiological responses to external stress and visa versa,” says Galper. “So if we are extremely stressed it can affect how our olfactory nerve cells respond to aromas.” says Galper.  In other words, your stress levels can change the way you process certain scents. So if you’ve gone from loving the scent of patchouli to suddenly wanting to throw every patchouli-scented candle in the garbage, your anxiety is a likely culprit.

A 2013 study put this theory to the test, and scientists showed people stress-inducing text and images (think: car crashes and wars) to see if it would change their sense of smell. “After anxiety induction, neutral smells become clearly negative,” Wen Li, one of the researchers behind the study, told Science Daily. “People experiencing an increase in anxiety show a decrease in the perceived pleasantness of odors. It becomes more negative as anxiety increases.” And why is that? According to researchers, in a “normal” (aka low-stress) smelling situation, it’s just the olfactory system that gets switched on, but when you start to get anxious, the emotional system also kicks into gear and becomes part of the processing stream.

While certain scents are considered to be universally calming, there’s no “one size fits all” essential oil for keeping you calm—particularly in times of high anxiety. Essential oils like rosemary, chamomile, lavender, pine, clary sage, or  marjoram have been shown to lower nervous energy and trigger a resting response in your body, so if your usual calm-down candle has stopped working, try introducing one of these into your routine. Just be warned: it may stop working the next time you flick on the news.