Aromatherapy Positively Affects Mood, EEG Patterns of Alertness and Math Computations
EEG activity, alertness, and mood were assessed in 40 adults given 3 minutes of aromatherapy using two aromas, lavender (considered a relaxing odor) or rosemary (considered a stimulating odor). Participants were also given simple math computations before and after the therapy. The lavender group showed increased beta power, suggesting increased drowsiness, they had less depressed mood (POMS) and reported feeling more relaxed and performed the math computations faster and more accurately following aromatherapy. The rosemary group, on the other hand, showed decreased frontal alpha and beta power, suggesting increased alertness. They also had lower state anxiety scores, reported feeling more relaxed and alert and they were only faster, not more accurate, at completing the math computations after the aromatherapy session.
Keywords: Aromatherapy; EEG; cognition; mood; lavender; rosemary
Aromas have been used throughout history for their medicinal and mood altering properties. Aroma molecules have direct effects on human behavior and physiology ranging from activation of memories to changes in mood or emotional states. Although much of what we know about these effects comes from anecdotal rather than empirical evidence (Buchbauer, Jirovetz, Jager, Plank and Dietric. 1993. Valnet. 1986), these effects may be explained by the close association between the olfactory and limbic systems (see Bear, Connors and Paradiso, 1996 and Lindsley and Holmes. 1984 for reviews).
Aromatherapy has been rapidly gaining in popularity. The essential oils involved in aromatherapy are highly concentrated essences extracted from plants through the process of distillation. Each oil is said to produce a predictable and reproducible effect on the user when its fragrance is inhaled (Sanderson and Ruddle, 1992; Valnet, 1986). Long and Schwartz (1987b; 1988) found, for example, that certain essential oils (lavender, spiced apple and eucalyptus) modified EEG activity including increasing relaxation as suggested by increases in alpha power. In another study Long and colleagues (Long, Herma, Schwartz and Cain, 1990), found that frontal beta EEG activity increased during lavender and decreased during spiced apple presentation. Parasuraman, Warm and Dember (1992) found that subjects exposed to a peppermint aroma were better able to sustain attention as assessed by an increase in skin conductance levels and sustained event related potential N160 amplitude across the attention task. Other studies have supported these EEG findings. For example Badia and colleagues recorded high frequency bursts in the EEG of subjects who were presented a peppermint aroma during sleep (Badia, Wesensten, Lammers, Culpepper and Harsh, 1990). Aromatherapy research has also shown behavioral changes including improved mood following presentation of chamomile oil (Roberts and Williams, 1992), positive affect while smelling vanillin (Miltner, Matjak, Diekmann and Brody, 1994), enhanced attention and performance on visual vigilance tasks following presentation of peppermint aroma (Warm, Dember and Parasuraman. 1991) and decreased anxiety and tension following lavender, spiced apple or eucalyptus aroma presentation (Long and Schwartz, l987b).
The present study examined aromatherapy effects on feelings of relaxation, anxiety, mood and alertness and on EEG activity and math computations. Two aromas were examined, an alerting odor (rosemary) and a relaxing odor (lavender). After the aromatherapy session the subjects who experienced the lavender aroma were expected to report less anxiety, better mood, and to show an increase in EEG power in the alpha and beta bands suggesting increased relaxation. In contrast, subjects who were presented the rosemary aroma were expected to show greater alertness as suggested by decreased alpha and beta power and better performance on the math computations. For example, in a previous EEG study subjects who were given massage therapy: (1) showed a decrease in frontal alpha and beta power (suggesting alertness); 2) showed an increase in frontal delta power suggesting relaxation); (3) reported feeling better, and (4) performed better in a cognitive task (Field et al., 1996).
The subjects were 40 faculty and staff members of the University of Miami Medical School (30 females, 10 males, M age = 30.9). They were middle socio – economic status (NI = 2.7 on the Hollingshead) and were 43% white, l5% African American, and 42% Hispanic. The participants were randomly assigned to the lavender or rosemary aroma conditions. The groups did not differ on the above demographic variables.
The aromatherapy was given by a research assistant to subjects seated in a special massage chair. Three drops of Lavender or Rosemary essential oil diluted to 10% concentration in grapeseed oil (provided by Aromatherapy Associates, Inc.) (now Miami Aromatherapy, Inc.) were placed on a cotton dental swab and presented in a 100 ml plastic vial which the subjects held about 3 inches from their nose for a period of three minutes. Subjects were instructed to breathe normally through their noses and sit quietly with their eyes closed.
The present study evaluated the effects of two commonly used odors on anxiety, mood, relaxation, alertness, math computations and EEG activity. Our findings support other research studies showing that certain aromas can positively influence mood (Roberts and Williams, 1992).
The Lavender group reporting feeling more relaxed and their increase in beta power supports previous findings on lavender’s ability to increase frontal beta power (Lorig et al., 1990), promote drowsiness (Buchbauer et al., 1991) and induce sleep (van Toller, 1988). Those who were exposed to the rosemary aroma showed increased alertness both by their self report and the decreases noted in Alpha and beta 1 power. These findings support the belief that rosemary is an alerting aroma (van Toller, 1988). The increase in frontal beta 2 power immediately after the rosemary aroma was removed suggests that its alerting effect might be short lived.
The math computation results suggest that although both groups performed the computations faster after the aroma session, only the lavender group showed improved accuracy on math computations following the sessions. This finding was surprising because the lavender group did not show the enhanced alertness EEG pattern that the rosemary group showed. Perhaps as reflected in both self report and EEG data, the lavender group was more relaxed and thus better able to concentrate. This and previous research indicate that aromas can effect psychological and physiological changes. Further research is needed on the underlying mechanisms of these effects.
(COMPLETE STUDY WILL BE SUPPLIED UPON REQUEST, PLEASE NOTE: MIAMI AROMATHERAPY WAS ORIGINALLY INCORPORATED AS AROMATHERAPY ASSOCIATES, INC. AND THE OILS PROVIDED IN THIS STUDY WERE NOT FROM AROMATHERAPY ASSOCIATES, LLC of the UK)
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