Think of scented candles, essential oils, bushels of smoking incense. The aroma of freshly baked cookies is bound to boost your mood, while a bouquet of great-smelling flowers is often just what’s needed to restore goodwill in a relationship. Indeed there’s no doubt that smells are powerful, and people have been trying to harness the power of smell to affect mood for over 6,000 years.

The human nose contains 5 million olfactory receptors (dogs have about 250 million) and they’re connected to the limbic system, an ancient part of the brain that helps regulate many things including emotion and memory. In fact, people with schizophrenia, migraines, and depression tend to fare worse on objective tests of smell – this sense, experts have construed, plays a pretty large role in mood.

So we know smell can affect mood on some level. But the question is, how much control do we have over that effect? Are there certain smell cocktails that can reduce stress or improve your sleep?

What is aromatherapy?

Aromatherapy is the practice of deliberately using particular smells to create particular outcomes. Normally, oils are infused with scents like vanilla, peppermint, lavender, or tea tree and then either applied topically, used in massage, heated with candles, or diffused into the air.

Does it work?

Well, the research is a little limited. Despite the public’s interest in using aromatherapy as a tool for relieving anxiety, depression, and chronic health conditions, there’s little evidence that common essential oils have definitive health-boosting qualities.

But as far as aromatherapy for insomnia goes, there has been some pretty encouraging research. One of the most well-known is a 2006 study of 42 women with insomnia, which found that four weeks of treatment with lavender aromatherapy helped to relieve the symptoms of insomnia in addition to reducing symptoms of depression. More research from the Journal of Alternative Complementary Medicine found that lavender aromatherapy promoted deeper sleep among thirty-one healthy sleepers, and it has been shown to boost sleep quality and reduce crying in infants. Combining lavender and rosemary was also found to improve stress levels among college students, evidenced by lower pulse rates and anxiety tests.

The thing is, these studies were all performed with pretty small sample sizes, so it’s hard to draw definitive conclusions—and there are certainly competing studies that will convince you there’s no concrete physiological benefit to be had.

Should you try it?

There seems to be little risk in experimenting; it’s noninvasive, inexpensive, and safe. If nothing has seemed to solve your insomnia thus far, the bulk of promising research has been performed with lavender, so that's a great scent to get started with. At the very least, it’s a good excuse to have your partner give you a scented massage!