Why is the smell of lavender linked with relaxation and sleep?

LavenderLavender (Lavandula angustifolia, sometimes known as Lavandula officinalis) is widely appreciated for its fragrance and therefore used in perfumes, soaps, shampoos, lotions and sachets for scenting clothes. The lavender plant thrives in sunny and stony environments and was originally found in Mediterranean Europe. The essential oil is obtained from the small, blue-violet flowers and the major component of lavender oil is β-linalool, which gives it a wooden smell (This chemical can also be found in many other scented plants.)

But apart from the nice smell, lavender oil has long been used as a mild sedative in complementary medicine, aromatherapy and folk medicine. In recent years, experiments with humans have evaluated lavender oil’s relaxation effects: these studies monitor the stress hormone cortisol and stress ‘markers’ in saliva (substances that are released by the body in stressful situations) such as the protein chromogranin A. In one experiment, 30 students performed an arithmetic test with half of the students exposed to lavender odour. The results showed that lavender had a relaxing effect as the students exposed to the smell of lavender produced less of the stress marker chromogranin A. Another study recorded blood pressure, heart rate, respiratory rate, and skin temperature while recording brain activities using an EEG machine. Comparing the effects of lavender oil to sweet almond oil, the researchers found that lavender oil caused decreases in blood pressure, heart rate and skin temperature. The subjects also ranked themselves as feeling more active, fresher and relaxed after sniffing the lavender.

The effect of lavender on sleep has also been studied. The inhaling of lavender odour during sleep has been observed to reduce the respiration frequency (you breathe in and out less), which is commonly used as an indicator of relaxation and sleep depth.

There is no easy explanation as to why lavender oil may help us to relax. The oil contains over 20 different chemicals and each one could have an effect on the body (or none). Linalyl acetate, a major component of lavender oil has been shown to help relax specimens of arteries that supply the brain in rabbits – suggesting it could lower blood pressure in the brain. Another study found that β-linalool and linalyl acetate also had a sedative effect on laboratory mice. It is believed that β-linalool and other chemicals in lavender oil inhibit the body’s ability to produce messenger molecules in the brain and nervous system, which may slow down signals from our brains to our muscles.

We can’t rest easy in the knowledge that lavender definitely helps us relax. Much of the research has featured very small numbers of subjects (too small to draw any absolute conclusions) and it is likely that many people sniffing lavender relaxed because they expected it to (the placebo effect). Bigger studies and also the use of double blind experiments are needed before we can lay the matter to bed.

Answer by Eileen Brandenburger

Photo Credit: kanonn via Compfight cc

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Article by Eileen Brandenburger

January 29, 2015

Eileen is a passionate chemist currently pursuing a PhD at the Manchester Institute of Biotechnology. Holding an MSc in chemistry, she left her home near Frankfurt to Germanise UK science. In between pipetting and attempting to be a proper biochemist, she likes to swap the lab coat for a tutu and perform on stage.

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