When feeling stressed and tired, take a restorative whiff of bracing lemon, enlivening rosemary or soothing lavender—or any other plant that has a pleasant scent. Scientists in Japan have reported the first scientific evidence supporting the idea that inhaling certain fragrances alters people’s gene activity and blood chemistry in ways that reduce stress.

The effects are attributed to linalool, a fragrant substance present in many plants and plant oils. When inhaled, linalool reduced stress-activated neutrophils and lymphocytes (two types of white blood cells) in the body to near-normal levels and restrained the activity of more than 100 genes that go into overdrive during stressful situations.

In their study, researchers noted that people have inhaled the scents of certain plants since ancient times to help reduce feelings of anxiety, fight inflammation and depression and induce sleep. Today, aromatherapy, or the use of fragrant oils to improve mood and health, is a popular form of alternative medicine. These findings could form a new basis for identifying the best fragrances to smell to dispel stress.

Source: American Chemical Society, 2009