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Ambient odor of orange in a dental office reduces anxiety and improves
mood in female patients
J. Lehrner
a,
*, Christine Eckersberger
b
, P. Walla
a
,G.PoÈtsch
a
, L. Deecke
a
a
Neurological Clinic, University of Vienna, Vienna, Austria
b
Private Office, Blumenfesse 32, 1110 Vienna, Austria
Received 15 February 2000; received in revised form 6 April 2000; accepted 25 May 2000
Abstract
Essential oils have been used as remedies for a long time in different cultures across the world. However, scientific proof of such
application is scarce. We included 72 patients between the ages of 22 and 57 while waiting for dental treatment 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. We assessed by means of self-report demographic and cognitive variables, trait and state anxiety, and current pain, mood, alertness, and
calmness. In this study, we report 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. Our data
support the previous notion of sedative properties of the natural essential oil of orange (Citrus sinensis). D2000 Elsevier Science Inc. All
rights reserved.
Keywords: Ambient odor of orange; Dental office; Anxiety; Mood
1. Introduction
Physiological and psychological effects of essential oils
have been acknowledged in folk medicine and aromather-
apy 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 de-
creased 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 signifi-
cant 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 com-
pared 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 depres-
sion. 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].
* Corresponding author. Neurologische UniversitaÈtsklinik, Allge-
meines Krankenhaus, WaÈ hringergu
Èrtel 18-20, A-1097 Vienna, Austria.
Tel.: +43-1-40400-3443 or +43-1-40400-3433; fax: +43-1-40400-3141.
E-mail address: hannes.lehrner@akh-wien.ac.at (J. Lehrner).
0031-9384/00/$ ± see front matter D2000 Elsevier Science Inc. All rights reserved.
PII: S0031-9384(00)00308-5
Physiology & Behavior 71 (2000) 83 ± 86
Given the potential of essential oils of altering physiolo-
gical 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 experi-
ence to be associated with fear and anxiety [6].
2. 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, corre-
sponding to five drops, of essential oil was applied to the
diffuser. The natural essential oil of Citrus sinensis supplied
by Primavera (Sulzberg, Germany) was used. The main
components of the essential oil was determined by gas
chromatography to be limonene 88.1%, myrcene 3.77%,
and a-pinen 1.19%, all other components were below 1%.
We assessed education, cognitive functioning (intelli-
gence quotient; IQ), pain (toothache), trait anxiety, state
anxiety, mood, alertness, and calmness by means of self-
report in the two study groups. Patients were selected
randomly in order to control for different dental procedures
(e.g., root canal drilling or dental cleaning). Upon arriving,
patients were registered and then were handed the ques-
tionnaires to be filled in while waiting for treatment. The no-
odor study group was tested first, followed by the odor
group. Importantly, answering the questionnaires was en-
tirely self-paced and dependent only on the speed of
patients. We did not measure fill-in time but in no case
was it longer than 20 min. Patients were told the purpose of
the study was to determine the association between pain and
mood. First, they completed a questionnaire asking for
demographic data. For assessing cognitive functioning
(IQ), patients completed the Wortschatztest (WST) [16] that
is a standardized vocabulary test with good correlation to
general intelligence as well as to education. Correlation
coefficient between WST IQ score and education assessed
as formal years of schooling was highly significant (r= 0.60,
p< 0.01) in our study population. Next, they were asked
about their current pain using an 11-point Likert scale
ranging from 0 (no pain at all) to 10 (cannot take the pain
anymore). Patients were next given a German version of the
State±Trait Anxiety Inventory (STAI) [19], a self-report
measure with demonstrated reliability and validity for
assessing trait and state anxiety. High scores indicate high
self-perceived anxiety. Subsequently, they were given the
Mehrdimensionale Befindlichkeitsfragebogen (MDBF) [20]
for assessment of current mood, alertness, and calmness.
Patients had to answer questions regarding mood, alert-
ness, and calmness on five-point Likert scales. Scale
reliability (Cronbach's a) is above 0.9 for all three scales.
Higher scores indicate more positive mood, high level of
alertness, and high level of calmness.
Finally, in order to control for possible awareness of the
presence of ambient orange odor patients were asked to
compare the waiting room with different waiting rooms they
may have encountered on four dimensions. Thus, patients
were asked whether the waiting room is (i) higher/lower/not
different in height, (ii) brighter/darker/not different, (iii)
smells more pleasant/more unpleasant/not different, (iiii)
has more newspapers/less newspapers/not different com-
pared to other waiting rooms.
3. 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 groups
(p> 0.2) indicating that all four groups were comparable in
terms of pain rating. Statistical analysis for trait anxiety
yielded a significant effect for sex (F(1,71) = 4.6, p< 0.04).
No other effect was significant (p> 0.7 for all). For state
anxiety there was no main effect of group (p> 0.5), nor
sex (p> 0.14), however a significant group sex interac-
tion (F(1,71) = 5.5, p< 0.03) was detected. For the measure
of mood there was no significant effect of group (p> 0.4).
However, the effect of sex (F(1,71) = 4.2, p< 0.05) and the
group sex interaction were significant (F(1,71) = 4.8,
p< 0.04). Statistical analyses of the dependent measure
alertness showed no main effect of group (p> 0.4) nor a
significant group sex interaction (p> 0.6). The effect of
sex (F(1,71) = 4.86, p< 0.03) was significant. For the
measure of calmness there were no significant group or
sex effects (p> 0.30 for all), however, a significant group
sex interaction (F(1,71) = 6.9, p< 0.01) was obtained.
Visual inspection of significant interactions indicated less
state anxiety, improved mood, and increased calmness
between odor group and no-odor group only for women.
Table 1 gives the details.
Awareness of presence of orange odor was analyzed with
regard to no-odor group and odor group. Analyses for the no-
odor group revealed that 5 (35.7%) of males reported ``smells
more pleasant'', 1 (7.1%) male reported ``smells more un-
pleasant'', and 8 (57.1%) males reported ``no difference'',
whereas 11 (47.8%) females reported ``smells more plea-
sant'', 3 (13.0%) females reported ``smells more unpleasant'',
and 9 (39.1%) females reported ``no difference'', respec-
J. Lehrner et al. / Physiology & Behavior 71 (2000) 83±8684
tively. There was no significant statistical differences be-
tween males and females (c
2
= 1.19; p> 0.55). Analyses for
the odor group revealed that 7 (38.9%) of males reported
``smells more pleasant'', 1 (5.6%) male reported ``smells
more unpleasant'', and 10 (55.6%) males reported ``no
difference'', whereas 8 (47.1%) females reported ``smells
more pleasant'', 1 (5.9%) females reported ``smells more
unpleasant'', and 8 (47.1%) females reported ``no differ-
ence'', respectively. There was no significant statistical
differences between males and females (c
2
= 0.26;
p>0.88). The subjects have not been asked directly, if
they had smelled on odor of orange in the waiting room.
They also have not been asked whether they detected the
odor of eugenol.
4. 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
effects. For instance, performance accuracy in a sustained
attention task was improved after peppermint and muguet
exposure only in female subjects [23] and lingering time in a
jewelry store was different under scent application for males
and females [7]. However, given prior reports indicating sex
differences for olfactory sensitivity, odor identification, and
odor memory (reviewed in Ref. [11]), our finding may be
due to sex differences in olfactory perception. A recent
study demonstrated gender effects on odor-stimulated func-
tional magnetic resonance imaging indicating more brain
activation in women compared to men after odorant appli-
cation [24]. This finding supports the behavioral data and
suggests physiologic differences between men and women
for olfactory perception.
Some sort of masking process may have been responsible
for the detected effect. The greatest sources of fear in dental
treatment are the anesthetic needle and the drill [6]. The
dental office is very often impregnated with the smell of
eugenol, since eugenates (cements containing eugenol) are
used in restorative dentistry on vital teeth. Eugenol odor
may be negatively associated with dental care in some
patients and thus may evoke intense unpleasant feelings
such as anxiety and fear. This is supported by the finding
that in patients with dental phobia the ``smell of the dental
office'' is given high importance [2]. Increased emotional
responses to eugenol in dental phobic patients measured by
psychophysiologic methods using autonomic nervous sys-
tem parameters [14] indicated a possible connection be-
tween fear of pain and the smell of eugenol. The reduced
state anxiety, raised mood, and increased calmness found in
our study could thus be due to the masking of negatively
charged eugenol odor in female patients. In male patients
olfactory influence on anxiety could play a minor role
perhaps because of their lesser olfactory sensitivity.
The observed effect could have been due the conscious
perception of the smell with the presence of the odor in the
office being a source of shared attentional resources,
serving as an orienting stimulus, and thus distracting
patients from attending to their internal bodily states. If
this is the case, the specificity of such an olfactory response
should be compared to other stimuli (e.g., music) in future
studies. Patients could have also formed some hypothesis
regarding the odor even though no overt reference to the
odor is made in the presence of the subjects. However, as
awareness analysis of presence of odor showed males and
females had a very similar distribution of ``smells more
pleasant/smells more unpleasant/not different'' responses in
the odor group indicating that conscious perception cannot
account for the results.
There are several limitations of the study that should be
addressed in future studies. First, since the odorant was
applied to the diffuser two times a day, it is possible that
the largest effects were seen during the times of the day
when the odorant concentration was at its highest and as a
consequence if more females were scheduled for dental
Table 1
Means, standard deviations, and the range of scores for each variable over the conditions
No-odor group Odor group
Variables Males Females Males Females
Age
a
31.4 4.2 (24 ± 30) 34.6 9.7 (22 ± 57) 38.2 9.6 (30 ± 69) 32.5 9.7 (21 ± 50)
IQ
b
107.4 13.7 (80 ± 129) 106.4 12.6 (80 ± 129) 114.7 9.1 (99 ± 129) 103.7 10.8 (81 ± 125)
Pain 3.2 1.7 (1 ± 6) 4.3 2.7 (1 ± 10) 3.3 2.1 (1 ± 7) 4.8 2.9 (1 ± 10)
Trait anxiety
b
33.4 5.0 (27 ± 46) 39.0 10.2 (26 ± 69) 33.5 6.9 (22 ± 50) 38.2 11.7 (23 ± 60)
State anxiety
a
33.8 6.3 (26 ± 46) 44.0 12.7 (24 ± 67) 37.7 12.5 (24 ± 62) 38.3 10.5 (21 ± 60)
Mood
a,b
34.4 2.8 (30 ± 38) 29.0 6.1 (16 ± 40) 33.0 5.8 (18 ± 39) 31.9 6.4 (12 ± 39)
Alertness
b
29.6 4.3 (21 ± 36) 25.9 6.9 (14 ± 40) 29.7 7.1 (17 ± 40) 27.4 6.9 (14 ± 38)
Calmness
a
31.8 3.6 (26 ± 37) 25.9 7.8 (8 ± 37) 29.4 7.9 (14 ± 39) 30.1 6.8 (15 ± 40)
a
Interaction sex group: p< 0.05.
b
Sex effect: p< 0.05.
J. Lehrner et al. / Physiology & Behavior 71 (2000) 83±86 85
work at those times of the day, gender effects might be
explained by this. Second, our patients were not screened
for upper nasal infection, allergies, etc.; however, the
patients sample likely contained patients with nasal dis-
ease. As patients were assigned randomly to the experi-
mental conditions we assume that nasal disease status was
similar across conditions. However, screening would be
helpful in detecting nasal disease status. Third, as patients
expect to undergo different dental procedures (e.g., root
canal drilling, dental cleaning) they will likely have dif-
ferent baseline anxiety. Unfortunately, in the current study
we have no such information available. Such procedures
should be documented and correlated to odor effects in
future studies. Fourth, in our study we did not measure
physiological changes induced by psychological stress
directly. Measuring levels of cortisol by way of saliva
sampling as an indicator of psychological stress could be
helpful in detecting physiologic effects of ambient odor.
Fifth, it has to be determined whether the reduction of
anxiety in the waiting room will also reduce anxiety when
seated in the dental chair.
In conclusion, our study supports the traditional use of
essential oils in altering emotional states. However, future
studies should also take up the suggestions of Jellinek [3]
and investigate direct effects of odorant molecules upon the
central nervous system, effects of odorant mixtures, as well
as those of single odor molecules, and effects of natural odor
mixtures compared to synthetic products.
Acknowledgments
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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