The effects of lavender (Lavendula angustifolium) baths on psychological well-being: two exploratory randomised control trials

The effects of lavender (Lavendula angustifolium) baths on psychological well-being: two exploratory randomised control trials

The effects of lavender (Lavendula angustifolium) baths on psychological well-being: two exploratory randomised control trials N. Morris Psychology Di...

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The effects of lavender (Lavendula angustifolium) baths on psychological well-being: two exploratory randomised control trials N. Morris Psychology Division, School of Applied Science, University of Wolverhampton, Wulfuna Street, Wolverhampton WV1 1SB, UK

SUMMARY. Objective: Two important aspects of psychological well-being are positive mood state and a positive outlook with respect to the future. This study investigates the use of lavender baths to improve these aspects of psychological well-being. Design: A single blind, randomised control trial. Setting: The participants’ home and interview rooms at the University of Wolverhampton. Participants: Eighty women not receiving treatment for psychological disorders who were staff or students at the University of Wolverhampton. Forty participated in Study 1 and 40 in Study 2. Intervention: Participants were randomly allocated to use either grapeseed oil or 80% grapeseed oil and 20% lavender oil in their bath for 14 days. Main outcome measures: In Study 1, the UWIST mood adjective checklist. In Study 2, the MacLeod and Byrne Future Events procedure. Results: In Study 1 psychologically positive mood changes were found after the bathing regimen for energetic arousal, tense arousal, hedonic tone and anger–frustration. Only anger–frustration showed a selective effect for lavender oil. In the second study negative responses about the future were selectively reduced after lavender oil baths. Conclusions: These results are encouraging and suggest further investigation using potential patients may result in the development of a useful procedure for improving psychological well-being. © 2002 Elsevier Science Ltd. All rights reserved.


Neil Morris PhD, Psychology Division, School of Applied Science, University of Wolverhampton, Wulfuna Street, Wolverhampton WV1 1SB, UK. Fax: +44 (0) 1902 321380; E-mail: [email protected]

It is no longer the case that health is seen simply as lack of disease. Rather ‘health’ is seen as incorporating ‘well-being’, a condition in which individuals attain mental and physical states that are viewed as being positive rather than neutral.1 It is also clear that physical ill health can result in increased anxiety and depression. This can produce a vicious circle that undermines physical recovery or the stabilising of medical conditions.2 Psychological well-being can be viewed as a state in which optimism and positive mood states predominate.3 To attain and sustain such a state may be difficult but simple, inexpensive procedures that at least enhance feel-

Complementary Therapies in Medicine (2002), 10, 223–228 doi: 10.1016/S0965-2299(02)00086-9

© 2002 Elsevier Science Ltd. All rights reserved.

ings of psychological well-being would nevertheless be a useful tool for health professionals. There is evidence that complementary therapies may provide such procedures. Studies employing aromatherapy, for example, have shown significant reductions in anxiety.4,5 There are a number of ways in which individuals can improve their psychological well-being without resort to psychotherapy. For example, a healthy diet and regular exercise are efficacious6 as are some relaxation techniques.7 In particular, strong claims are made for the efficaciousness of aromatherapy8 which has been shown to produce positive mood shifts.9 A typical, self-administered aromatherapy regimen consists of diluting an essential oil with



Complementary Therapies in Medicine

for example grapeseed oil, and adding this to a warm bath. The procedure is said to be relaxing and allows the absorption of the oil whose chemical constituents then gently ‘medicate’ the individual.10 Lavender oil is often highlighted as being particularly efficacious.11 Much of the evidence for this efficacy remains anecdotal. The two studies reported in this paper attempt to put this on a more scientific footing. Healthy volunteers followed a regimen of bathing with either lavender oil or a placebo (grapeseed oil) and their psychological well-being in terms of mood-state and optimism about the future was determined before and after the study using clinically valid psychometric instruments.

STUDY 1—MOOD Factor analytic studies of mood suggest that mood is not a uni-dimensional construct i.e., there are a number of different mood dimensions.12 A factor analytic study of the University of Wales Institute of Science and Technology (UWIST) Mood Adjective Checklist,13 henceforth termed the UWIST, suggested that three factors dubbed energetic arousal, tense arousal and hedonic tone parsimoniously partitioned the variance. Two less well-defined dimensions, general arousal and anger–frustration, also emerged. This model is very similar to Thayer’s12 solution but has the advantage, in Britain, of using adjectives that are familiar to the target population.14 Matthews et al.13 report appropriate reliability and validity data suggesting that the UWIST is a valid instrument for measuring mood states. To appreciate why mood, as measured by the UWIST, is an appropriate measure of psychological well-being it is necessary to have some idea of what each dimension means, in psychological terms. An individual scoring high on energetic arousal would report feeling vigorous and alert while high tense arousal scores imply nervousness and perceived stress. Individuals scoring high on hedonic tone report feeling cheerful and happy. General arousal and anger–frustration are not well defined in this instrument and can only be interpreted cautiously. Great care must also be taken in designing mood studies. Unlike personality dimensions mood dimensions are not stable over time. A given mood score, for example, hedonic tone, will change across the day with fluctuations in arousal levels, blood sugar and other cyclic physiological variables.12 It is important, therefore, to test at the same time of day and to compare responses after the first bath and after the last bath, rather than prior to the first bath and after the last bath. UWIST scores are likely to have changed after a bath. The point of interest is whether, following the bath each day, the mood state is more positive after 2 weeks. In this study volunteers were recruited to take part in a ‘relaxation study’ that involved following

a regimen of taking baths with oil added once per day for 2 weeks. Given the exploratory nature of this study, the duration selected was somewhat arbitrary, there is no useful literature to provide guidance on an appropriate duration. Half the participants bathed with base oil (grapeseed) only added to their baths. The remaining participants added base oil and lavender oil, an oil almost universally recommended by aromatherapists as being beneficial both physically and psychologically,11,15 to their baths. It was hypothesised that if there were improvements in mood state at the end of the study then this might be due to the bath procedure per se (given that the test has good test–retest validity it is unlikely that any changes would simply be due to taking the test twice) unless a significant interaction showed that improvement was greater with lavender oil. Both grapeseed oil and lavender oil are aromatic so any placebo/experimenter effect is likely to emerge as a main effect that will not contaminate the interaction term.

METHOD Forty female participants were recruited from staff and students at the University of Wolverhampton. The mean age was 28.2 years (S.D. 7.1). Males were excluded because almost all volunteers were female. Individuals who consented, in writing, to participate answered a brief questionnaire that was used to exclude those who knew they were pregnant, those with cardiovascular problems, and those with asthma or skin allergies. The questionnaire included a copy of the procedure and a tear off consent sheet that was signed before proceeding. Confidentiality was assured. Those who consented arranged a brief, 10 min, meeting with an investigator to pick up materials. At the meeting they were given the appropriate materials, and instructions on how to use them, plus a contact number to ring if they had any problems or queries. Finally before proceeding into the study each individual was required to apply one drop of their oil to their forearm for 30 min. If this produced any irritation they were told to return the material and not proceed with the study. The study received approval from the Ethics and Safety Committees of the University of Wolverhampton. No participants failed to complete the study but approximately 20 potential participants withdrew before the study commenced after being briefed.

Materials Each participant was provided with two copies of the UWIST mood adjective checklist, a stamped addressed ‘jiffy’ bag, a stamped addressed envelope, one diary sheet a dropper bottle and an information sheet with a brief health questionnaire and a ‘tear off’ consent form.

Effects of lavender bath on psychological well-being


Procedure Staff and students resident on the main campus of Wolverhampton University were approached, initially via notice boards, and requested to participate in a study investigating the effect of baths on relaxation. They were told that the study required them to take one bath per day, at approximately the same time each day, and to add oil, provided by the investigators, to the water. They had to fill in a diary sheet that required them to note each day they took a bath with the oil and at what time the bath was taken. This diary sheet was also used to note any unusually stressful events that might affect the study. It was explained that they should fill in the questionnaire immediately after the first bath and mail it in a stamped addressed envelope provided as soon as possible after the bath. A second copy of the questionnaire was to be completed 14 days later after the last bath and mailed in a stamped addressed ‘jiffy bag’ together with the remnants of the oil. The date stamps on the envelopes were used to verify that the questionnaire had been filled in promptly. All materials were identical except that 20 participants received a dropper bottle containing grapeseed massage oil and 20 participants received a bottle containing 80% grapeseed oil plus 20% (by volume) lavender essential oil. The participants were not aware that there were two types of oil being used and the identity of the materials was not revealed to them. They were told that the material was ‘bath oil’. Allocation to condition was random. The jiffy bags were numbered 1–40, odd numbers were grapeseed, even numbers were lavender. Random number tables were then consulted to determine the order in which the jiffy bags were to be distributed. Each participant was given a ‘starting date’ but chose their own time of bathing. On day 1, the participant would run a bath and then add three pipette measures (3 ml) from their bottle. They then bathed for 10 min. This was recorded on their diary sheet and the UWIST mood adjective questionnaire was filled out after reading the instructions (which had also been explained to them at the initial meeting). The UWIST was sealed in an envelope and mailed to the investigator. A bath was taken at roughly the same time each day for 14 days and this, plus any necessary deviations from the procedure, were

recorded on the diary sheet. After the final bath the UWIST was filled out immediately and placed in the jiffy bag together with the diary sheet and the remainder of the oil. This was posted to the investigator. Upon receipt the participant was telephoned, thanked and debriefed. The data from a given participant was deemed to be usable if they had taken at least 10 baths in the 14 days, the level of oil in the bottle was appropriately depleted and all paperwork was appropriately completed and returned within 3 days of the study completion. ‘Valid’ baths occurred at the same time as the first bath ± 1 h. No participants were excluded because of allergic reaction to the skin test and no one used the telephone advice number or failed to take the minimum number of baths.

RESULTS The five dimensions on the UWIST mood scale were analysed separately. Each dimension was subjected to a two way, mixed design analysis of variance with type of oil used (grapeseed or grapeseed plus lavender) as a between subject factor (n = 20). The two administrations of the test (after the first bath and after the last bath) were treated as a repeated measures factor. The means and S.D. are shown in Table 1. On the energetic arousal dimension there was no main effect of oil type (F(1, 38) < 1) but energetic arousal increased after the bathing regimen (F(1, 38) = 26.7, P < 0.0001). There was no interaction (F(1, 38) < 1). With tense arousal, the F-ratios for oil type and interaction were again less than unity. Tense arousal dropped after bathing for a fortnight (F = 40.0, P < 0.0001). A similar pattern emerged for hedonic tone, the oil type F-ratio was less than unity, the interaction was non-significant (F = 4.6, P > 0.05) and hedonic tone increased after the bathing regimen (F = 43.7, P < 0.0001). The anger–frustration (A–F) dimension revealed no effect of oil type (F < 1) but there was a significant drop in A–F after treatment (F = 50.2, P < 0.0001) and a significant interaction (F = 7.1, P < 0.01) which simple effects analysis16 showed to be due to a greater reduction in the group receiving lavender

Table 1 Means (S.D.s) (in parentheses) of mood scores at the beginning and end of an aromatic bath series Mood dimension EA TA HT A–F GA

Grapeseed beginning 21.6 16.5 25.1 10.8 28.5

(5.1) (5.0) (5.6) (4.7) (5.2)

Grapeseed end 25.1 13.9 27.9 8.6 28.6

(4.1) (4.4) (4.5) (3.5) (3.5)

Lavender beginning 21.1 18.3 22.5 11.9 29.1

(4.5) (5.8) (5.5) (4.3) (4.3)

Lavender end 24.7 13.5 27.9 7.2 28.6

(4.0) (3.4) (3.9) (3.0) (4.5)

Scores for two groups of participants, bathing in either grapeseed oil (grape) or grapeseed oil plus lavender oil (lav), are shown for energetic arousal (EA), tense arousal (TA), hedonic tone (HT), anger–frustration (A–F) and general arousal (GA).


Complementary Therapies in Medicine

oil (P < 0.01). The final dimension analysed, general arousal, showed no significant effects at all (all F-ratios <1). To summarise, ‘positive’ effects of bathing, irrespective of whether lavender oil was added to the bath, were found for energetic arousal, tense arousal and hedonic tone. General arousal was unchanged and A–F was selectively reduced by lavender oil. This was the only specific effect of lavender. The UWIST values at the beginning of the study are very similar to those collected from female shop workers in Wolverhampton14 suggesting this sample is ‘normal’ although one cannot generalise this to men.

STUDY 2—FUTURE EVENTS Several studies17–20 have demonstrated that pessimism about possible future events is an important component of depression. It is likely that ‘rehearsal’ of negative thoughts about the future is a factor in maintaining depression21 and that a procedure that reduced a negative mind set about future events would be efficacious, at least when levels of depression were sub-clinical. Such ‘milder depression’ is common22 and may respond to aromatherapy. Optimism/pessimism is a more stable dimension than mood in that it is an enduring state suggesting that it is methodologically sound to take baseline measures before the bath regimen begins and to then measure again after the cessation of the study.

METHOD Participants Forty females recruited from the staff and students of Wolverhampton University, mean age 26.2 years (S.D. 2.5) volunteered to participate in this study. None of these participants took part in the earlier study and they were recruited from a different campus. Again many potential participants withdrew before the study commenced. Most were unwilling to participate in a study lasting 2 weeks.

for eliciting explanations for future likely events replaced the UWIST mood adjective checklist and this required a number of procedural changes relating to administration of this questionnaire. In the ‘future events’ (FE) procedure participants were given a booklet with a statement on each page. The statements referred to possible future events and each statement, for example, “You will have lots of good times with your friends”, was presented twice. On one presentation it was accompanied by the instruction “Please think of as many reasons as possible why this will NOT happen”. On the other presentation the NOT was deleted. All item ordering, including positive and negative versions, was randomised for each participant thus producing unique booklets for each participant. The participant was given 1 min to respond verbally to each ‘scenario’. The FE procedure was carried out twice. The first administration occurred at an interview with the investigator on the day before commencement of the baths. Participants returned the diary and bottle to the investigator within 24 h of the last bath and the second FE administration occurred at this time. This second session was always at the same venue as the first FE presentation (usually in the participants home). All other aspects of the procedure were identical to Study 1. The study received approval from the Ethics and Safety Committees of the University of Wolverhampton. All positive responses were summed, as were all negative responses, while any general responses (those referring to an impersonal future rather than the fate of the individual herself) were disregarded. Participants had been instructed, with illustrative examples, what constituted ‘personal’ and ‘impersonal’ responses and two practice examples were examined at each administration before proceeding to the main questionnaire. There were four items in the questionnaire each with a positive and negative version creating an eight page booklet. Thus each participant had a positive and a negative score for before and after the bath regimen. Scorers were unaware of the treatment participants had received. Once again there were no exclusions as a result of allergic reaction and the telephone help line was not used.


Materials and procedure The materials and procedure were similar to Study 1 except that the MacLeod and Byrne18 procedure

Analysis of variance on the positive responses revealed no effect of oil type (F(1, 38) = 2.6,

Table 2 Means (S.D.s) (in parentheses) of scores on the MacLeod and Byrne future events questionnaire at the beginning and end of an aromatic bath series Valency of scale +Ve −Ve

Grapeseed beginning

Grapeseed end

Lavender beginning

Lavender end

12.5 (4.8) 9.6 (4.4)

11.5 (4.1) 8.1 (4.7)

13.4 (6.5) 10.8 (4.1)

13.9 (4.0) 6.5 (3.5)

Scores for two groups of participants, bathing in either grapeseed oil or grapeseed oil plus lavender oil, are shown for positive events (+ve) and negative events (−ve).

Effects of lavender bath on psychological well-being

P > 0.05), time of testing (F(1, 38) < 1) and no interaction (F(1, 38) = 2.4, P > 0.05). For negative responses there was no effect of oil type (F < 1) but there was a significant reduction in the number of negative responses after bathing (F = 68.7, P < 0.0001). There was also a significant interaction (F = 37.0, P < 0.0001) that simple effects showed to be due largely to a much greater drop in response rate in the Lavender group (P < 0.01). The means and standard deviations are shown in Table 2. To summarise, the procedure had no effect on the rate of positive responses to possible future events but when participants bathed in lavender there was a marked reduction in the number of negative responses generated.

DISCUSSION The results of Study 1 show that the procedure was efficacious in elevating energetic arousal, reducing tense arousal and increasing hedonic tone suggesting that bathing per se improves mood. One might argue that participants are merely conforming to the investigators expectations given that there is no selective effect of lavender oil. However this would not explain why there was no effect on general arousal and why there was a selective effect on anger–frustration. The most likely explanation seems to be that daily bathing is mood enhancing. The selective effect of lavender on anger–frustration suggests a reduction in aggressive feelings but should be treated with caution as the dimension has poor psychometric properties. Study 2 shows no increase in positive views about the future, possibly because there was a high positive response rate prior to the commencement of the bathing regimen. This is characteristic of performance levels in the control groups of clinical studies. However, the negative response rate is reduced in both groups indicating that, as in Study 1, there may be psychological benefits from some aspect of the bathing regimen per se. In this study, however, there is an additional reduction in negative views of the future, indicated by the significant statistical interaction, specifically associated with the lavender bath condition suggesting that adding lavender to baths may help to reduce pessimism in individuals who are not clinically depressed. Further research on more general populations should establish whether or not this is the case. These studies were carried out on groups that were from a non-clinical population and who are not representative of the general population, especially as there were no male participants. One might also suspect that a university population is somewhat atypical, and this may explain why compliance with the procedure was so high. All drop outs from the study occurred prior to the start of the study, i.e. these were individuals who read the informed consent sheet and declined to participate. All those


giving reasons said this was because of the extended duration of the study. Nevertheless, the population from which this sample was drawn is a large one and some aspect of the bath procedure appears to have produced significant improvements in psychological well-being. Mood is elevated by the end of the study, irrespective of the oil used, but there is a specific effect of lavender oil on reducing negativity about future events. It is not clear whether the effect is confined to lavender oil or whether any pleasant fragrance will produce this effect. While these procedures are unlikely to replace psychotherapy and pharmacological interventions in the treatment of severe psychological disorders they may well be useful for treatment of psychological responses to everyday life-stresses. However these findings have been derived from an exploratory study. While they suggest that this is likely to be a fruitful research direction further work is needed before firm conclusions emerge.

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16. Kirk R. Experimental Design and Procedures for the Behavioural Sciences. Belmont, CA: Brooks/Cole, 1968. 17. MacLeod A, Salaminiou E. Reduced positive future-thinking in depression: cognitive and affective factors. Cogn Emotion 2001; 15: 99–107. 18. MacLeod A, Byrne A. Anxiety, depression, and the anticipation of future positive and negative experiences. J Abnorm Psychol 1996; 105: 286–289. 19. Byrne A, MacLeod A. Attributions and accessibility of explanations for future events in anxiety and depression. Br J Clin Psychol 1997; 36: 505–520.

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