Thursday, January 5, 2012

Essential oils: Lavender - the science about the aromatherapy

Lavender essential oil is reported to have many awesome benefits, but the main ones appear to be reducing anxiety, reducing pain, and helping with sleep. So let's take a look at some of the science behind the aromatherapy claims about lavender. (As a note, unless otherwise indicated, we're dealing with Lavandula angustifolia, English or French lavender.)

In this study, 30 volunteers were divided into two groups. Both inhaled oxygen through a mask for 5 minutes before being poked with needles. One group had masks with two drops of 2% lavender essential oil diluted in jojoba oil and the other didn't. The conclusion was that lavender essential oil provided a significant decrease in stress levels and pain levels are reported by the volunteers.

For alternate view, take a look at this study that showed that post-operative patients didn't report feeling less pain when inhaling lavender oil! 

In a study on anxiety and aromatherapy during exams, "the use of lavender and rosemary essential oil sachets reduced test-taking stress in graduate nursing students as evidenced by lower scores on test anxiety measure, personal statements, and pulse rates." (McCaffrey R ; Thomas DJ ; Kinzelman AO, Holistic Nursing Practice (HOLISTIC NURS PRACT), 2009 Mar-Apr; 23(2): 88-93 (17 ref)) In another study on anxiety and aromatherapy on nurses,  "The sample of the study was composed of 50 students who constituted the study group and 45 students who were the controls. The study group was exposed to lavender inhalation. The mean anxiety score of the study group (42.76 - 12.48) was lower than that of the control group (51.51 - 12.21), and the difference between the groups was statistically significant (p = .002). This study shows that aroma inhalation decreases examination anxiety." (Kutlu AK ; Yilmaz E ; Cecen D, Teaching & Learning in Nursing (TEACH LEARN NURS), 2008 Oct; 3(4): 125-30 (39 ref))

In this study on dementia patients and lavender, the researchers concluded that aromatherapy wasn't effective for reducing agitation in severely demented patients because "There is significant evidence in the neurologic and neuropsychologic literature that persons with dementia have impaired olfactory abilities...this study found no support for the use of a purely olfactory form of aromatherapy to decrease agitation in severely demented patients." The writer of this letter to the editor about a study they conducted argues that "the present study shows lavender aroma therapy to be useful in treating such patients apart from neuroleptics."

In experiments with rats, one study found that "...these experiments suggest that lavender oil does have anxiolytic effects in the open field, but that a sedative effect can also occur at the highest doses." (Shaw D ; Annett JM ; Doherty B ; Leslie JC, Phytomedicine,, 2007 Sep; 14(9): 613-20).

As for sleeping, this study from 2005 found "Outcomes favor lavender, and a larger trial is required to draw definitive conclusions." The report on this study in which a "group of 30 women and their infants were randomly assigned to one of three groups —1) a lavender bath oil group, 2) a nonaroma bath oil group or 3) a lavender bath oil group in which the mothers received an advertisement stating the bath oil "helps calm babies when they get irritated" or "helps settle them down before bedtime"—to assess the effects the lavender aroma on infants' stress levels, crying and sleep behaviors". The conclusion of the study authors was that "These data suggest that infants with irritability and sleep problems could be calmed by this aroma and may experience more restful sleep." (I'm not totally happy with this study because I didn't find it in a peer reviewed journal, but it is reporting what others are reporting with regards to sleep, so I'm quoting it here.) In this study, the conclusions were that "Lavender increased the percentage of deep or slow-wave sleep (SWS) in men and women. All subjects reported higher vigor the morning after lavender exposure, corroborating the restorative SWS increase. Lavender also increased stage 2 (light) sleep, and decreased rapid-eye movement (REM) sleep and the amount of time to reach wake after first falling asleep (wake after sleep onset latency) in women, with opposite effects in men. Thus, lavender serves as a mild sedative and has practical applications as a novel, nonphotic method for promoting deep sleep in young men and women and for producing gender-dependent sleep effects."

Beyond sleep, lavender’s sedative and calming effects have been noted using various physiological measures during waking. Lavender lowers heart rate and blood pressure (Nagai et al., 2000; Romine et al., 1999) and changes electroencephalographic (EEG) frequency and contingent negative variation (Torii et al., 1988), suggesting increased drowsiness. Lavender also increases beta activity (Diego et al., 1998; Lorig et al., 1990), decreases alpha activity (Masago et al., 2000), and increases theta activity (Klemm et al., 1992; Lorig and Schwartz, 1988). Such findings concur with self-reported relaxing mood states induced by lavender exposure (Diego et al., 1998; Goel and Grasso, 2004; Motomura et al., 2001). In addition, lavender slows reaction times (Karamat et al., 1992; Yagyu, 1994) and reduces performance of cognitive tasks (Ludvigson and Rottman, 1989; but see Diego et al., 1998).

I could quite honestly spend all day quoting studies I've seen on humans of all types and animals (mostly rats, but some mice) and we'd still come to the same conclusion: The studies are showing that inhaling lavender essential oil can decrease anxiety and stress and the expression of same as well as increasing sleep. Very interesting!

Join me tomorrow for more on the science of lavender essential oil when we take a look at ingesting or putting the oil on our skin!

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