Essential oils may help reduces clients’ blood pressure; however, according to new research, long term exposure to them could have a detrimental effect on blood pressure rates.

According to the study published in the European Journal of Preventive Cardiology, the essential oils which form the basis of aromatherapy for stress relief are also reported to have a beneficial effect on heart rate and blood pressure following short-term exposure.

However, on the downside, those beneficial effects were reversed when exposure to essential oils lasted more than an hour, a press release from the European Society of Cardiology noted.

The study was performed in men and women working in spas in Taipei, Taiwan. One hundred young, healthy nonsmoking spa workers taking part in the study visited the study center on three occasions (about once a week), when each volunteer was exposed to vapours of essential oils released from an ultrasonic ioniser for two hours, the press release noted.

During this time and on each visit, three repeated measurements—resting heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP)—were taken from each spa worker in the small study room, according to the press release. Before each participant entered the study room, 100-percent pure bergamot essential oil was vaporised for one hour.

Results showed (after adjusting for age, sex, BMI, day of the week, and visit order) that the room’s VOC level was significantly associated with reduced blood pressure and heart rate for between 15 and 60 minutes after the start of exposure.

However, after exposure for more than 1 hour – from 75 to 120 minutes after the start of exposure—VOC levels became associated with an increased 15-minute mean blood pressure and heart rate.