Ambient odor of orange in a dental office reduces anxiety and improves mood in female patients
Introduction
Physiological and psychological effects of essential oils have been acknowledged in folk medicine and aromatherapy for a long time [22]. Citrus fragrances have been particularly attributed with mood-enhancing properties by aromatherapists and “successful experiments were carried out with oils of citrus fruits on patients affected with hysteria or depression” [15].
Based on such claims several researchers studied the psychological and physiological effects of citrus smells. Increased magnitude of the contingent negative variation (CNV) indicative of stimulation [4] for citrus notes was reported whereas decreased CNV magnitude indicative of relaxation was found for lemon [12]. Increased alpha band of micro-vibration and inhibited CNV suggesting mental relaxation [21] after orange odor exposure was found. Physiological studies documented changes in heart rate after lemon odor exposure [5]. Orange oil increased the activity of the parasympathetic nervous system by 12% and decreased the activity of the sympathetic nervous system by 16% [13]. Behavioral studies reported facilitated recall of a word list under lemon oil application [1] and a decrease in error rate in a letter cancellation task [13]. Using lemon odor in an environmental fragrance system that functions through the central air-conditioning system of a building, a significant reduction of key entry errors in video display operators was documented [12]. In a simulated retail environment, significantly different product evaluations and shopping behaviors were found under ambient orange scent as compared to a no scent condition [18].
Animals studies found evidence that citrus fragrance can restore stress-induced immunosuppression [17] and may have potential antidepressant effects in rats [10]. This result was followed up in a clinical study in patients with depression. A mixture of citrus oils was capable of reducing the necessary treatment doses of antidepressants, normalizing neuroendocrine hormone levels, and immune function in depressive patients [9]. Ambient lemon odor was also found to decrease the number of health symptoms in young healthy subjects [8].
Given the potential of essential oils of altering physiological and psychological states, the goal of our study was to determine, in a natural setting of a waiting room, the effects of natural essential oil of orange on patients waiting for dental treatment. The setting of a dental waiting room was chosen because previous evidence suggested dental experience to be associated with fear and anxiety [6].
Section snippets
Materials and method
We included 72 patients between the ages of 22 and 57 in our study. The participants were assigned to either a control group (14 men, 23 women) or to an odor group (18 men and 17 women). Ambient odor of orange was diffused in the waiting room through an electrical dispenser in the odor group whereas in the control group no odor was in the air. The dispenser was hidden from the patients' view. Every morning and every noon approximately 0.25 ml, corresponding to five drops, of essential oil was
Results
We performed separate 2×2 analysis of variance (ANOVA) (group: odor vs. no-odor; sex: male vs. female). Statistical analyses indicated that the groups did not differ regarding education (p>0.2), however, groups showed significant sex differences for IQ (F(1,71)=4.7, p<0.04) and a significant sex×group interaction for age (F(1,71)=4.3, p<0.05). Thus, in subsequent statistical analyses we included age and IQ as covariates. ANOVA for degree of toothache detected no statistical difference between
Discussion
The results of this study indicate that exposure to ambient odor of orange has a relaxant effect. Specifically, compared to the controls, women who were exposed to orange odor had a lower level of state anxiety, a more positive mood, and a higher level of calmness.
The finding of a sex effect was unexpected because it has been rarely described in the literature. One explanation could be that this phenomenon has received little scientific attention until now, with only a few studies exploring sex
Acknowledgements
We would like to thank Ms. Maggie Lee Huckabee for making helpful comments on earlier drafts of this paper. After the experiment, the patients were shortly debriefed about the true nature of the study by the dentist and provided informed consent.
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