Nurses are no strangers to stress, anxiety, and burnout. Even at the best of times these afflictions can wreak havoc on quality of life and work performance (Jennings, 2008).
And the Covid Era is, well, hardly the best of times. Anxiety, defined as “an excessive and uncontrollable worry,” is of particular concern among nurses: it can impede decision-making and increase the probability of making errors (Melnyk et al., 2021). It’s essential, for the well-being of staff and patients alike, that we take care of the mental health of our healthcare practitioners (Zhang et al., 2020).
Can essential oils help?
Indeed, they can. A 2020 article entitled “The Effect of Music Therapy and Aromatherapy with Chamomile-Lavender Essential Oil on the Anxiety of Clinical Nurses: A Randomized and Double-Blind Clinical Trial” published in the Journal of Medicine and Life found that both aromatherapy and music therapy, individually and in combination, were cost-effective non-pharmacological interventions that significantly reduced anxiety in clinical nurses (Zamanifar et al., 2020).
Before we get into the nuts and bolts of this paper, let’s do a quick background check to make sure it’s worth reading at all. These days, there’s a glut of publications that vary wildly in quality. Some journals are rigorous while others are downright predatory and stuffed with rubbish (Sharma and Verma, 2018).
In this case, a google search reveals that the Journal of Medicine and Life is peer-reviewed and indexed in PubMed, a free and widely accessible search engine maintained by the US National Library of Medicine (NLM). That’s a good start. Historically, PubMed was the gold standard in biomedical literature, a database that exclusively indexed high-quality papers. Sadly, standards have since slackened and some predatory journals have weaseled their way in. Let’s take the additional step to check if the journal in question is also indexed in the more highly selective NLM database MEDLINE (it is!). MEDLINE is the NLM’s “premier bibliographic database,” one that you can trust (for now) to curate credible content (Ossom Williamson and Minter, 2019).
Now that we’ve vetted our source, let’s take a closer look at the methodology of our study. To assess the impact of aromatherapy and music therapy on anxiety, researchers selected 120 nurses from clinical wards (Adult Emergency, Pediatric Emergency, Adult ICU, Pediatric Internal, Pediatric Infectious, Neonatal ward, Pediatric ICU, Oncology, Internal ward, and Infants ward) of Besat Hospital in Sanandaj, Iran.
Subjects were picked via purposeful sampling, a technique widely used in qualitative research where information-rich cases are chosen to make efficient use of limited resources. With this approach, subjects are typically selected based on their communication skills, availability, willingness to participate, and knowledge of and experience with a phenomenon of interest. Purposeful sampling can be contrasted with random sampling. By randomly selecting subjects, researchers ensure that findings can be generalized to a larger population by controlling for confounding factors and minimizing potential selection bias (Palinkas et al., 2015). In this study, the nurses’ willingness to participate in the study was a significant factor in their selection.
The nurses were randomly assigned to one of four test groups, with 30 subjects per group. Let’s take a minute here to contemplate sample size. A sample size of 30 is typically considered the statistical “magic number,” a minimum value at which researchers trust that they can reasonably extrapolate findings to a larger population. Depending on the context, it’s a good rule of thumb, but not necessarily a strict dictate. Smaller sample sizes can, for example, sufficiently demonstrate proof-of-concept in pilot studies and pre-clinical trials.
In most cases a sample size of 30 or greater is preferred, but bigger is also not necessarily better. Overly large samples waste financial and human resources when more modest numbers can elicit equally practicable findings (Faber and Fonseca, 2014).
Inefficient resource usage in bloated samples is just one limitation. In the era of “Big Data,” researchers draw information from disparate data sources involving potentially thousands of subjects. These large studies, however, often lack pertinent information, even key variables, and can magnify biases that arise from flaws in study design. The Big Data approach can spawn a mess of potential biases, including sampling error, measurement error, multiple comparisons errors, aggregation error, and errors associated with the systematic exclusion of information. Importantly, large sample size alone fails to improve the validity of most studies in epidemiology, health services research, and clinical trials. Instead, it’s “representativeness” — the ability of a sample to accurately reflect a larger population — that’s more influential in generating meaningful results (Kaplan et al., 2014).
One final consideration on the topic of sample size: large sample sizes can produce extremely statistically significant results with zero practical significance. An article entitled “The large sample size fallacy,” published in the Scandinavian Journal of Caring Sciences, explains that practical significance is determined by the size of an observed effect, not by a statistically significant p-value. The author indicates that, by using smaller sample sizes, researchers can be assured that statistical significance invokes real-world meaning. He writes:
The hidden advantage of working with small sample sizes is that statistical significance is fundamentally related to practical significance in terms of larger effect sizes.
In other words, statistically significant results will generally not be reached in a small sample study unless the effect sizes are large (Lantz, 2013).
Sample sizes strongly influence the outcomes of studies, and the types of conclusions we can draw from them. The present study meets our threshold requirements for sample size, so let’s move on.
Nurses were divided into the following four groups:
- Music therapy
- Aromatherapy with chamomile-lavender essential oil
- Combined music therapy and aromatherapy
- Control (no intervention)
In the music therapy intervention, subjects listened to their preferred musical genre (traditional, pop, and classic) with headphones for 20 minutes per shift during three consecutive shifts and during breaks.
The aromatherapy group was exposed to chamomile-lavender essential oil for 20 minutes per shift during three consecutive shifts and during breaks. The specific methodology of essential oil preparation is oddly unclear, so I’ll quote from the article itself. According to the authors:
1.5% chamomile-lavender essential oil was prepared from Zardvand Pharmaceutical Company. Then, at Shahid Beheshti School of Pharmacy, after confirming the scientific name, distillation with water was applied for this essential oil and was then diluted in sesame oil by 5%. Three drops of chamomile-lavender essential oil were poured on a pre-prepared no absorbable pad and were placed 20 cm from the nose.
…I have questions.
If the original essential oil from the Zardvand Pharmaceutical Company is 1.5%, how was it prepared and what was it diluted with? What was the ratio of chamomile to lavender essential oil? What does “distillation with water was applied for this essential oil” mean? Did they really dilute with sesame oil by 5% (a relatively small and meaningless reduction), or did they dilute it to 5% (1⁄20 of the original concentration)?
The precise methodology will likely remain a mystery unless we query the authors directly, but I think we can reasonably conclude that a modest amount of essential oil was used, and still elicited a significant effect.
The third experimental group received combined music therapy and aromatherapy for 20 minutes per shift during three consecutive shifts and during breaks.
The control group did not receive any intervention.
Anxiety was assessed for all subjects after three work shifts to establish baseline post-shift anxiety levels, and again after the interventions to determine their effect. Anxiety was measured using the Beck Anxiety Inventory (BAI), an inventory commonly used to evaluate the severity of anxiety symptoms.
Researchers confirmed that there were no initial differences between the four groups that might bias the outcome. They investigated demographic factors including sex, marital status, educational level, number of children, and age, and found that there were no significant differences in the distribution of these factors between the groups. Anxiety levels pre-intervention were comparable in all four groups.
And now we’ve arrived at the exciting portion of the paper where we acknowledge that something real and valuable happened! Mean anxiety scores were found to be significantly lower in the three experimental groups following intervention, as compared with pre-intervention anxiety scores. Post-intervention anxiety scores were also significantly lower in the three experimental groups relative to the control group.
Both aromatherapy and music therapy alone and in combination were found to reduce nurses’ anxiety, even with just a few brief treatments during three consecutive work shifts.
These findings hint at the possibility of creating more human-friendly conditions in hospitals with simple, economical, and non-invasive interventions.
The present study built on and confirmed previous research that identified ameliorative effects of music and aromatherapy on dental anxiety in pediatric patients, anxiety in patients undergoing mechanical ventilation, and anxiety in breast cancer patients. This particular study was the first to investigate the efficacy of lavender-chamomile essential oil aromatherapy and music therapy on reducing anxiety in clinical nurses.
There are several things this study did well that can promote our confidence in the results. First of all, it was a clinical trial. When it comes to complex mental and behavioral health issues clinical studies are superior to animal studies and — perish the thought — petri dish experiments. Secondly, subjects were randomly assigned to the four groups, and demographic parameters were analyzed to ensure there were no initial differences between the groups. The researchers were blinded as to which subjects belonged to which group in order to prevent biases. Blinding was achieved with the cooperation of an assortment of research assistants who administered questionnaires and collected data, while a principal researcher performed the final data analysis. Finally, this study was conducted as part of a masters thesis by researchers with no vested financial interest in the outcomes. Keep an eye on the money; “funding bias” exerts a well-established impact on research findings (Krimsky, 2013).
While this study had many virtues, the authors also acknowledge a few limitations. One hindrance in this study, according to the authors, was “the occurrence of situational problems and mental issues for nurses during the research, which was left out by the researchers.” This could mean aaaaaanything. What to do? Fortunately, there’s a large body of evidence indicating that aromatherapy and music therapy can be helpful in reducing anxiety. Scientific practice, like many human activities, is a collective process. No single experiment establishes an objective “truth” about the universe, but together many experiments can indicate the likely veracity of certain principles.
A second limitation of this study is that, “due to the rotation of the work shifts of nurses, sampling in three consecutive shifts was a problem.” This isn’t ideal, and we can’t be certain what kind of impact those glitches in protocol had on the outcomes of the study. But it’s also a reminder to recognize how incredibly complicated clinical research is. Achieving absolute standardization in the chaotic daily lives of 100+ people is nigh impossible. Life is messy, and empirical research will always collide with that complexity.
As I read through this paper, several questions came up for me. How long were the nurses’ shifts? How long between shifts? How many breaks did nurses have? In other words, how many interventions occurred total, over what period of time? What was the control group doing in the 20 minute intervals that the intervention groups were otherwise engaged in music-listening and aromatherapy? Is it possible that performing any intervention whatsoever had a placebo-like effect; was it experienced by nurses as a form of care and support? Indeed, studies have shown that supportive work environments and nurses’ perceptions of being valued positively impacted stress levels, well-being, and work performance (Jennings, 2008; Melnyk et al., 2021).
I’m also curious if the music therapy and aromatherapy interventions would impact nurses’ work performance and perceived quality of life. The authors conclude that, because music therapy and aromatherapy reduced anxiety, they could therefore “increase the level of accuracy and attention and improve the quality of nurses’ work.” Without a follow-up study measuring these specific outcomes, however, it’s purely conjecture.
A final point to consider: Even though this study describes itself as “double-blind,” the subjects must be aware of the sounds and smells they’re experiencing. This is one of the challenges of aromatherapy research — the subjects are consciously aware of odorants, and thus we lose the capacity to discriminate between purely physiological effects, vs. the psychological effects of the oils. Some researchers have circumvented this challenge by performing studies where subjects are exposed to aromatherapy in their sleep (Ko, et al., 2021).
To sum it up, let’s not underestimate the value of simple non-invasive interventions in reducing anxiety for those in high-stress occupations. And, as you go about reading scientific literature on your own, be sure to evaluate the validity of your sources, seek out randomized double-blind clinical trials, keep an eye on details like sample size, and read similar studies to put the research in context.
Faber, J., & Fonseca, L. M. (2014). How sample size influences research outcomes. Dental Press Journal of Orthodontics, 19(4), 27–29. https://doi.org/10.1590/2176-9451.19.4.027-029.ebo
Jennings, B. M. (2008). Work stress and burnout among nurses: Role of the work environment and working conditions. In R. G. Hughes (Ed.), Patient Safety and Quality: An Evidence-Based Handbook for Nurses. Agency for Healthcare Research and Quality (US). http://www.ncbi.nlm.nih.gov/books/NBK2668/
Kaplan, R. M., Chambers, D. A., & Glasgow, R. E. (2014). Big data and large sample size: A cautionary note on the potential for bias. Clinical and Translational Science, 7(4), 342–346. https://doi.org/10.1111/cts.12178
Ko, L.-W., Su, C.-H., Yang, M.-H., Liu, S.-Y., & Su, T.-P. (2021). A pilot study on essential oil aroma stimulation for enhancing slow-wave EEG in sleeping brain. Scientific Reports, 11, 1078. https://doi.org/10.1038/s41598-020-80171-x
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Lantz, B. (2013). The large sample size fallacy. Scandinavian Journal of Caring Sciences, 27(2), 487–492. https://doi.org/10.1111/j.1471-6712.2012.01052.x
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Sharma, H., & Verma, S. (2018). Predatory journals: The rise of worthless biomedical science. Journal of Postgraduate Medicine, 64(4), 226–231. https://doi.org/10.4103/jpgm.JPGM_347_18
Zamanifar, S., Bagheri-Saveh, M. I., Nezakati, A., Mohammadi, R., & Seidi, J. (2020). The effect of music therapy and aromatherapy with chamomile-lavender essential oil on the anxiety of clinical nurses: A randomized and double-blind clinical trial. Journal of Medicine and Life, 13(1), 87–93. https://doi.org/10.25122/jml-2019-0105
Zhang, Y., Wang, C., Pan, W., Zheng, J., Gao, J., Huang, X., Cai, S., Zhai, Y., Latour, J. M., & Zhu, C. (2020). Stress, burnout, and coping strategies of frontline nurses during the covid-19 epidemic in wuhan and shanghai, china. Frontiers in Psychiatry, 11, 1154. https://doi.org/10.3389/fpsyt.2020.565520