Scent is a powerful thing. Catch a whiff of chlorine, and you might be flooded with memories of childhood pool days and summer fun. Open an old, dusty book, and you’ll be transported to your college or elementary school library. Smell brown butter browning on the stove, and you’ll swear you can taste your mom’s chocolate-chip cookies fresh out of the oven. Smell the stench of tequila across the bar, and get an unwelcome reminder of drunken nights and bad decisions from your younger years — or maybe last weekend.

But in addition to evoking memory or simply providing pleasure to our noses, scent is thought to alleviate a myriad of physical, mental, and emotional ailments, boosting your overall health. The practice of aromatherapy is built entirely upon this phenomenon.

What is aromatherapy?

Aromatherapy and the use of essential oils date back several thousand years and have appeared throughout history in various places and cultures. “The history of using aromatic substances originates from primitive times,” says Hellen Yuan, a certified aromatherapist and the founder of HELLEN, an LA-based, sustainable aromatherapy company. “We have discovered leaves, berries, roots, and florals were mixed to help people with illness, spiritual experience, and mood enhancers.”

Written records suggest that the Sumerians and Babylonians who lived in Mesopotamia used plants medicinally more than 5,000 years ago, and the Egyptians were known to use perfumed oils, scented barks, and resins in 3000 B.C.E. The practice transcended Greek and Roman history, where aromatic baths and massages and scented products were heavily used for beauty and health respectively. It wasn’t until 1937 that the term “aromatherapy” was actually introduced, though, when Rene Maurice Gattefosse coined the word in his book Gattefosse’s Aromatherapy.

Despite its storied past, however, the holistic therapy has experienced something of a renaissance over the last few decades. Thanks to an increased interest in natural remedies, aromatherapy has become a mainstay in many people’s lives and the solution they rely on for all sorts of issues.

“The star of aromatherapy is the essential oil,” Yuan explains. “Essential oils are also known as ‘volatile oils’ and are extracted from the plant’s leaves, roots, or petals, and it’s important to use genuine and authentic essential oils derived directly from plants to avoid synthetic, reconstructed, or adulterated versions.”

Essential oils can be used through diffusers, vaporizers, or aromatic inhalers, but those who plan to apply oils directly on their skin via lotions, creams, balms, massage oils, or bathing blends must dilute them with a base in order to address underlying issues while maintaining safety and avoid any irritation.

Even if you’ve never purchased an essential oil or a diffuser of your own, though, you more likely than not have used aromatherapy in some form. Vick’s Vaporub, the tried-and-true, age-old antidote to the common cold, cough, or flu, for example, is rich in eucalyptus, cedar leaf, and nutmeg essential oils and relies upon their strong fragrance to awaken your sense of smell and break up phlegm and congestion. Or perhaps you’ve used a lavender-filled eye mask to combat sleeplessness and lull yourself into slumber. The thinking behind such products is rooted in aromatherapy’s effect on the olfactory system.

“Research has shown that aromatherapy can calm stress and is capable of affecting the nervous system, and essential oils possess various therapeutic qualities, such as anti-inflammatory, antiseptic, febrifuge [fever-reducing], and many more,” says Yuan. “Holistic aromatherapy is dynamic, as various products have been created to support everything from stress, anxiety, headaches, insomnia, skin problems, musculoskeletal issues, sinus problems, and respiratory problems.”

But does it actually work?

But as aromatherapy grew in popularity as a treatment for serious health conditions like major depression, memory loss, and even some effects of cancer, many have wondered if there is any data that prove the therapy can successfully treat such conditions. There remains no evidence-supported research to show that aromatherapy or the use of essential oils can actually cure any illnesses or ailments, though some studies have explored the benefits that the therapy can have on certain mental health and emotional issues.

One such study by the American Association of Nurse Practitioners found that, in tandem with clinical methods, the use of essential oils can reduce overall patient anxiety and stress, but notably, it advocates for further research on the efficacy of such approaches. The U.S. Patent Application Publication, meanwhile, notes that “nasal direct access to the limbic brain provides mental support and neurological stimulations or calm for stress-disorders, anxieties, depression, and other emotional conditions.”

Other research has been conducted in recent years examining the use of essential oils and aromatherapy to aid sleep issues, including those experienced by cancer patients during their traditional treatment. “We are seeing aromatherapy now supporting cancer patients during treatments and seeing improvement in their sleep quality,” a National Library of Medicine study found. “Aromatherapy was effective in improving 95% of participants’ sleep.” A further study in the same publication found that oils like lavender, lemon, frankincense, bergamot, orange sweet, and peppermint were effective in alleviating nausea and encouraging relaxation among cancer patients in the UK.

Although the legitimacy of aromatherapy for treatment of serious physical and mental health problems remains unclear, the use of essential oils has proven a successful remedy to plenty of other, less grave issues. In addressing acne, for instance, tea tree oil is helpful because of its anti-inflammatory and antimicrobial properties, while the use of essential oils like thyme, lavender, and rosemary have been shown to improve the effects of hair loss and alopecia.

It’s important to note, however, that even those findings which prove aromatherapy’s benefits are not yet supported by clinical trials, so there’s still plenty of work to be done before essential oils are considered a replacement for or alternative to traditional medication or treatment. Essential oils do not require approval by the FDA in the U.S., but there are relatively few known side effects so long as you’re using authentic oils and diluting them as needed. There is therefore little downside to experimenting aromatherapy if you’re looking to alleviate anxiety, stress, or insomnia, but before you ditch all your Aspirin and Pepto-Bismol to make room for dozens of essential oils, you should consult a professional.

“Safety is everything in working with essential oils,” Yuan advises, “and having custom-made products to suit your needs with a trained certified clinical aromatherapist is most productive to getting support to heal your primary concerns.”