Aromatherapy is widely used for stress relief. But most scientific studies of how it works have been inconclusive and frustrating. A new study of Taiwanese spa workers now finds aromatherapy capable of lowering people's blood pressure and heart rate. The catch is that it stops doing so after about an hour.
The researchers used oil of bergamot in their study. Bergamot is a yellow, pear-shaped orange best known for its use as a flavoring in Earl Grey tea.
During the first hour, the higher the room's VOC content, the more an employee's heart rate and blood pressure dropped. At 45 minutes, average systolic blood pressure had dropped by just over two points and heart rate had decreased by just over two beats per minute.
Researchers exposed 100 spa employees in various spa centers in Taipei, Taiwan to vapors produced from one hour's ultrasonic atomization of oil of bergamot in a study room. Workers stayed in the room for two hours and had their blood pressure and heart rate continually monitored. The concentration of volatile organic compounds (VOCs) in the air was also monitored.
During the first hour, the higher the room's VOC content, the more an employee's heart rate and blood pressure dropped. At 45 minutes, average Systolic pressure Systolic pressure had dropped by just over two points and heart rate had decreased by just over two beats per minute. But after an hour, the opposite began to happen, until at two full hours in the room, average systolic blood pressure had risen by just over two points, while heart rate had increased by an average of 1.7 beats per minute.
The simplest interpretation of these results is that oil of bergamot has a general relaxing effect on people for about an hour and that people who enjoy aromatherapy might want to limit the length of their sessions to an hour or so — too much of a good thing is no longer therapy.
Exposure to volatile organic compounds (not necessarily those from aromatherapy) has been linked to harmful conditions such as asthma in hairdressers. Researchers have found that exposure to VOCs for over an hour in hair salons can lead to increases in markers of inflammation and oxidative stress. Perhaps after more than an hour, the main effect of the VOCs both in hair salons and in aromatherapy is that of air pollutant.
In any case, the Taiwanese study provides some scientific backing of aromatherapy's usefulness, as well as suggesting that aromatherapy works best in moderation.