The effect of odor on mood was examined by exposing subjects to the scents produced by the essential oils of lavender, bergamot, sandalwood, and rosemary. Subjects taken from the Marywood University student population completed the Profile of Mood States pre and post the presentation of an odorant. The research indicates that individuals become more relaxed when presented with multiple relaxing odorants simultaneously when compared to a no odor group, single relaxing scent presentation, or single stimulating scent presentation. Specific moods effected were tension, vigor, and fatigue. Gender, past exposure to aromatherapy, and smoking habits seemed to have various mood effects when exposed to an odor. The majority of subjects also reported experiencing a memory when exposed to an odor, further implicating an emotional reaction.

Aromatherapy is a concept that dates back 5,000 years (Fischer-Rizzi, 1990). Originating in Europe, the practice entails the use of essential oils derived from plant extracts to promote healing physiologically and psychologically (Nelson, 1997). Traditionally, the essential oils are either massaged into the body, used in the bath, or diffused into the air (Cerrato, 1998). This is based on the belief that certain odors promote therapeutic effects that range from healing minor skin irritations to altering mood states (Butcher, 1998). Up until recently, this concept has been without scientific merit (Jellinek, 1994). The purpose of this study is to examine the therapeutic effects of scents currently believed to possess anti-anxiety and anti-depressive properties.

Empirical investigations suggest that essential oils may be effective for the treatments of pain and anxiety (King, 1988). Findings that are of interest to the psychological and psychiatric communities are claims that there is an interaction of odor and mood (Diego, Jones, Field, Hernandez-Reif, Schanberg, Kuhn, McAdam, Galamaga, and Galamaga, 1998). Despite there being little research on aromatherapy, members of the medical community have reported its integration to relax patients diagnosed with serious illnesses, such as in the case of HIV (Albert, 1998). It has also been used to calm cancer patients (Nelson, 1997). This recent rise in the use of odor to influence mood calls for further examination in order to quantify and validate the practice (Butcher, 1998). If support for the findings concerning mood alteration due to an odorant were found reliable and valid, aromatherapy may be substituted for psychotropic medications in the treatment of mood disorders (King, 1988).

An odor that has gained popularity and noted in research for its effects as reducing anxiety is lavender (Ludvigson and Rottman, 1989). Lavender has been found to correlate with slower heart rate, lower systolic blood pressure, lower diastolic blood pressure, and lower arterial pressure (Romine, Bush, and Geist, 1999). It has also been found to decrease muscle tension (Jellinek, 1994).

Studies that monitored brain activity through the use of an EEG have reported that Lavender decreases theta waves, an effect shown to represent relaxation (Lorig and Schwartz, 1988). Lavender has also been used to induce sleep with patients that suffer insomnia (Hirsh, 1995).

Another use of lavender in the medical field has been to calm patients undergoing magnetic resonance imaging (Romine, Bush, and Geist, 1999). This relaxing effect may be explained physiologically by findings that suggest emotional structures, such as the amygdala, respond to olfactory stimulation (Zald and Pardo, 1997).

Studies that rely on self report measures, such as the POMS, report that individuals exposed to lavender are more happy and feel pleasant more than when not exposed and compared to subjects who are not exposed at all (Knasko, 1992). Other scents that have been found to have similar relaxing effects are bergamot (anti-anxiety) and sandalwood (calming) (Torii, Fukuda, Kanemoto, Miyanchi, Hamauzu, and Kawasaki, 1988).

In contrast, it has been reported that rosemary has an overall having an uplifting effect. Physiologically, this scent has been observed as a stimulant (Cerrato, 1998). This arousing effect has been supported by findings based on self-report as well as EEG analysis (Diego, et al., 1998).

The concept of the ability of odor to alter mood states is a premise that has justified the operation of commercial fragrances and colognes (Baron, 1981). Commercial scents are usually combinations of synthetic and/or natural essences (Green and Freeman, 1991). Due to the specificity of the olfactory receptors, combining scents stimulates a greater number of cilia increasing the stimulation that is sent to the olfactory bulb and the structures that receive information thereafter (Axel, 1995). This would infer that a combination of scents would increase the aroma-therapeutic effects of odorant inhalation (Fischer-Rizzi, 1990).

Aromatherapy is based on the claim that there are reliable mood alterations as a result of exposure to specific scents (Diego, et al., 1998). Preliminary studies have found evidence that contradicts this assumption, such as the findings that lavender increased tension and anxiety (Lawless, 1991). This raises the issue of whether or not the psychological effects of the scents are empirically validated or reliable.

A concept that seems to be key in the examination of odor and mood interdependence is the notion of hedonics. This is the degree of pleasantness an odor is perceived as possessing (Jellinek, 1994). Hedonics has been noted as eliciting emotional responses such as fear, withdrawal, and happiness (Zald and Pardo, 1997). Such reactions to olfactory stimulation imply that there is an interplay of neurological structures responsible for the processing of olfaction and emotion (King, 1988).

Due to the inconsistencies and unexplored nature of aromatherapy, it is the purpose of the present study to explore the therapeutic effects of the seemingly established scents lavender and rosemary. This investigation also intends to examine the concept of combining odorants for the purpose of increased therapeutic effects. Based on the popular findings of recent research and 5,000 years of aromatherapy, it is hypothesized that lavender will have anti-anxiety effects and rosemary will have anti-depressant effects more so than not being exposed to either scent or compared to each other. Furthermore, it is believed that the combination of the odorants will enhance the therapeutic relaxing effect more so than either single scent or not being exposed to a scent.

Participants

Fifty-five volunteers participated from the Marywood University population. Most subjects responded in order to fulfill an undergraduate psychology class research requirement or receive extra credit. Of the 55, 11 were male and 44 were female. The sample was primarily Caucasian (91%) native to the United States. The mean age was 22 ranging from 18 to 78 years. Fifty-five percent were enrolled at the freshman level; the remaining 45% consisted of high school graduates, college students at various stages, and one person who holds a doctorate.

Apparatus

Assessment of mood was measured through the use of the Profile of Mood States (POMS) (McNair, et al., 1992). This 65-point emotional adjective rating scale consists of six scales; tension-anxiety, fatigue-inertia, anger-hostility, confusion-bewilderment, vigor-activity, and depression-dejection. The six scales reflect reliable and identifiable mood or affect states, as found through factor analysis. Adjectives that make up the mood or affect scales will be rated on a range of 0 (not at all experienced) to 4 (extremely experienced). Overall, the test represents a "rapid, economical method of identifying and assessing transient, fluctuating affective states" (McNair, et al., 1992, p.1).

The essential oils used were supplied from Les Herbes of Huntington, Long Island. Lavender was used for the single relaxing odorant condition and rosemary was presented for the stimulating condition. A combination of equal parts of lavender, sandalwood, and bergamot were presented for the condition assumed to produce a greater relaxing response than the single odor presentation.

An aromatherapy diffuser manufactured by Leyden House Limited of New England was used to scent the room. The scent produced from the essential oils was diffused cyclically every 30 minutes. Allowing the machine to complete one cycle produced each condition. This was sufficient for scenting the size room used for this experiment. No odor was presented to the control group.

For the 20 minutes that subjects were confined to the conditioned room, a neutral task was presented. The purpose was to prevent boredom and frustration that may result from confinement. The neutral task consisted of a packet of eight mazes, ten letter searches, and six word searches. All puzzles were generated through the use of an education web site provided by the Discovery Channel. Words used were neutral, as indicated by research produced by Brown and Ure (1969).

Procedure

Participants were gathered for each condition according to the order in which they volunteered. Participants were brought to a neutral beige colored room that was void of wall art, distracting décor, or detectable odor. Upon entering the room, the subjects were presented with a consent form, already placed on the desk in front of each chair. After reading through the consent and all questions were addressed, the participants completed a demographics sheet and the Profile of Mood States. They were instructed to report the feeling that they were having at that very moment. The demographics sheet also asked whether or not the person used tobacco products, incense, essential oils, candles, or perfumes.

Once this pretest was completed, the participants were moved into another similar lab room. For 20 minutes, the subjects were exposed or not exposed to an odor, depending on the condition prescribed. During the 20 minutes, the participants worked on the neutral task. Subjects were told that the task presented was not being assessed and used as a tool to prevent boredom. Instruction was given to not interact with other members of the group or work on any outside material.

After 20 minutes, the subjects were given another Profile of Mood States to complete reporting on the feelings they were having that very moment. Along with this mood assessment, subjects were asked to rate the odor detected as well as whether or not it spurred any memory. Upon completion, subjects were debriefed and all questions were addressed.

The Profile of Mood States yielded scores of tension-anxiety, fatigue-inertia, anger-hostility, confusion-bewilderment, vigor-activity, and depression-dejection under the condition of odor manipulation. Generally, scores reported for each scale were average for pretest and post-test administration with the exception of vigor (high) and depression (low)(see Table 1).

The effects of odor on mood were analyzed through a 2 x 4 (Time X Odor) ANOVA with an alpha level of .05. One statistically significant interaction resulted for time x odor for the mood termed fatigue-inertia, when considering all participants, F (3,51)= 2.7, p = .05. Subjects reported that fatigue and inertia, rated by such terms as exhausted, weary, and sluggish, was accentuated by the lavender and rosemary presentation and decreased during the simultaneous presentation of lavender, sandalwood, and bergamot. The control group, that experienced no odor, also experienced a decrease on the fatigue-inertia scale (see Figure 1).

An all-inclusive analysis also produced a significant main effect for vigor-activity over time, F (3, 51) = 14.4, p = .00. Overall, there was a decrease in vigor-activity, as reported by such terms as lively, energetic, and cheerful (see table 2). Factoring out certain variables also resulted in main effects for vigor over time. Women were found to report feeling less vigorous from pretest to post-test for all odor presentations, F (3, 39) = 9.8, p = .01. Individuals that reported using candles for aromatherapeutic purposes, also felt significantly less vigorous after trials, F (3, 29) = 9.0, p = .01. Similar significant main effects were also found for vigor-activity levels when smokers were factored out of the analysis, F (3, 44) = 13.3, p = .00.

Excluding smokers from the sample resulted in a marginally significant interaction between tension and odor, F (3, 44) = 2.5, p = .07 (see Figure 2). Main effects for tension over time resulted when factoring out men from the sample, F (3, 39) = 4.4, p = .04. Across all conditions, women reported being less tense after trails were complete (see Table 3). Individuals that reported using aromatherapy candles in the past yielded scores that also resulted in a similar pattern of main effects, F (3, 29) = 8.3, p .01. In this case, the pattern was a decrease of tension and anxiety, described as shaky, panicky, and restless, across all conditions except for the control, which resulted in an increase (see Table 4). This was also found when analyzing data for individuals that reported using incense for aromatherapeutic purposes, F (3, 12) = 7.1, p = .02.

Post-hoc scores yielded through the use of paired t-tests for each odor presentation. For lavender, there was a significant difference for vigor-activity, t(12)= 2.3, p = .04 that represented a general decrease in the feeling (see Table 5). Rosemary also showed a near significant decrease in vigor-activity, t(14) = 2.0, p = .06 (see Table 5). The post hoc measures also implicated significant changes for the simultaneous presentation of lavender, sandalwood, and bergamot from pretest to post-test. Unlike the lavender or rosemary presentation, the lavender, sandalwood, and bergamot mixture yielded results that significantly implicate a reduction of tension, t(14) = 2.2, p = .04 (see Table 5). The fatigue-inertia scale showed a similar significant change, t(14) = 2.3, p = .04 (see Table 5). Significant differences were not found when analyzing the control group data.

Memory was analyzed using a univariate analysis of variance. The significant relationship was shown between the presentation of an odor and the experiencing of a memory, F (3, 49) = 4.5, p = .01. There were no significant results for the degree of emotion and odor presentation.

The two interactions implied by this study support the hypothesis that a combination of relaxing odorants simultaneously presented would have a greater effect than a single relaxing odorant presentation. Results of this nature strengthen the argument of odor's effect on altering mood states suggested by the research of King (1988) as well as the claims of lavender scent being crucial to relaxation (Romine, Bush, and Geist, 1998). It further supports research that places sandalwood and bergamot among odorants responsible for decreasing tension and anxiety (Torii, et. al, 1988

The alteration of mood in response to odor suggested by this study support the assumption that odor alters mood. The interaction found between odor and time for fatigue-inertia implicates an increase in this mood when lavender and rosemary were presented singularly. The simultaneous presentation of lavender, sandalwood, and bergamot results in a reduction of fatigue-inertia scores. This could implicate a more therapeutic use for the combination of scents; however, the no odor group reported a similar reduction. An interpretation of this recorded effect may be one that credits the combination of relaxing odorants to speeding up the process of fatigue recovery. If it is accepted that no odor creates a similar relief of fatigue and that single relaxing and stimulating odorants increase the feeling, it may make sense to assume that combining odorants accentuates a regression to the mean. Under this assumption, the hypothesis that the presentation of combined odorants produces increase therapeutic effects than single odorant presentation is supported.

This hypothesis is also supported by the post hoc measures that suggest a decrease in tension for the mixed odorants from pretest to post-test. This could be further insinuated by the findings that individuals exposed to this condition decreased in fatigue-inertia. During the analysis of post hoc measures, there were no effects for the control group from pretest to post-test. This allows for an unopposed acceptance of the notion that lavender, sandalwood, and bergamot have a greater therapeutic effect when combined than lavender or rosemary presented alone, or exposure to no odor at all.

In respect to replication of past research, this study fails to support rosemary as a stimulating agent. Contrary to current belief in the field of aromatherapy, rosemary produced a more relaxed mood from pretest to post-test. Since this study provides further controversy to the psychological effects of this scent, future investigation would be recommended.

Some gender differences were noted, although one of the limitations of this study is the lack of male participants. Males only represent 20 percent of the sample population. With this limitation, the results report that there were significant main effects for vigor-activity and tension-anxiety over time. For both mood states, there was a decrease in the feeling reported. This was found among all odor presentations.

It was also found that individuals who use aromatherapeutic products, such as candles are more likely to be effected psychologically by an odor presentation. The specific moods significantly effected were tension-anxiety and vigor-activity. This may be due to an expectation that comes from using aromatherapeutic products similar to findings that mentioned in research compiled by Jellinek (1994). This notion of expectancy should be further researched for the direct effects on mood alteration.

Analysis of the hedonics of the odors did not result in any difference across odor presentations. All means were average and similar to each other. For this reason, this study fails to make any comparison for the effect of hedonics on mood during an odor manipulation.

Although the data was analyzed for including tobacco users and non-tobacco users, most mood subscales showed no significant differences in the output. When smokers were removed from the sample, it was found that there was a marginal interaction between odor and time for the mood state of tension-anxiety. A main effect describing a decrease in vigor-activity was also found once tobacco users were factored out of the sample. This may support findings that implicate a lasting effect of odor on the areas of the brain that process emotion, not giving the manipulated odor the opportunity to have an effect (Zald & Pardo, 1997). Another possibility may be that individuals that smoke wear clothing tainted by the scent. It may also be due to the factoring out of the nervous qualities associated with the use of tobacco products. Perhaps individuals who choose not to use tobacco products are more relaxed than those who do use them. This could be a topic of further investigation.

The limitations of the current study include a poor distribution of gender and age. This was due to the availability of the university subject pool used in this convenience sample. This research is preliminary and warrants further investigation for the purpose of replication and development of the concept.

Overall, this study implicated odor's effect on mood states. To further implicate the relationship of the olfactory system to emotional processing, it was reported that 91 percent of the participants experienced a memory. Memory is processed in the Limbic System, the portion of the brain that also processed emotion (Zald & Pardo, 1997). This finding suggests that further investigation should take place focusing on memory and odor. It also suggests that the scents produced by essential oils have the capability to alter mood states. In this case, aromatherapy passes the test; however, it is obvious that more empirically based studies are necessary. Specific odors have not been reliably tested for potential psychological effects, as seen with the contrite findings of rosemary.

Research on odor and mood may be applied to clinical practice if empirical validation was established. Altering mood states through the use of essential oils is an affordable, easy to administer alternative to psychotropic medications. Although, it may not be found to be effective with all individuals, it would be less toxic to the system and less likely to cause non-reversible physiological side effects. In general, this is a solution that has potential to be easily accepted and sought after by the current generation that seeks better living through chemistry.

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Table 1

Pretest and Post-test Means for Six Subscales Measured by the POMS: Comparing Potential Low and High Scores

POMS Subscales Range Pretest Post-test

Tension- Anxiety 0-36 15.5 14.58

Depression-Dejection 0-60 18.9 18.7

Anger-Hostility 0-48 14.8 14.9

Vigor-Activity 0-32 23.6 19.8

Fatigue-Inertia 0-28 14.1 14.0

Confusion-Bewilderment 0-28 12.5 12.4

Table 2

Means and Standard Deviations for Scores Yielded on the Vigor-Activity Scale of the POMS: Pretest and Post-test

Vigor-Activity Pretest Post-test

Lavender M = 22.8 SD = 7.2 M = 18.4 SD = 5.6

Rosemary M = 24.2 SD = 5.9 M = 19.8 SD = 6.6

Lav-Sand-Berg M = 24.7 SD = 5.6 M = 20.8 SD = 7.3

No Odor M = 22.5 SD = 4.2 M = 19.8 SD = 6.7

Table 3

Means and Standard Deviations of the Pretest and Post-test of Tension-Anxiety for the Odor Presentations: Women Subjects

Tension-Anxiety Pretest Post-test

Lavender M = 15.1 SD = 3.6 M = 14.3 SD = 4.0

Rosemary M = 14.0 SD = 3.5 M = 13.7 SD = 4.3

Lav-Sand-Berg M = 17.7 SD = 3.7 M = 15.0 SD = 3.2

No Odor M = 15.6 SD = 4.2 M = 14.6 SD = 4.3

Table 4

Means and Standard Deviations of the Pretest and Post-test of Tension-Anxiety for the Odor Presentations: Aromatherapeutic Candle Users

Tension-Anxiety Pretest Post-test

Lavender M = 15.6 SD = 3.4 M = 14.3 SD = 3.8

Rosemary M = 13.8 SD = 3.2 M = 12.0 SD = 3.0

Lav-Sand-Berg M = 18.1 SD = 4.1 M = 15.3 SD = 3.3

No Odor M = 15.8 SD = 6.9 M = 16.3 SD = 6.6

Table 5

Means and Standard Deviations for Significant Findings During Post Hoc Measures

Condition Mood Pretest Post-test

Lavender(N=13) Vigor M = 22.8 SD = 7.2 M = 18.4 SD = 5.6

Rosemary(N=15) Vigor M = 22.2 SD = 5.9 M = 19.8 SD = 6.6

L-S-B (N=15)Tension M = 16.9 SD = 4.1 M = 14.7 SD = 3.0

L-S-B (N=15)Fatigue M = 15.3 SD = 5.6 M = 13.1 SD = 4.4

Figure Captions

Figure 1. Pre-test and post-test means for fatigue-inertia subscale on the POMS.

Figure 2. Pre-test and post-test means for tension-anxiety subscale on the POMS for non-smokers.

I was unable to transfer the figures to the net - if interested, you may e-mail me a request a copy.