Each person took part in three half-day sessions where they were exposed to both scents. Participants were monitored for blood pressure and heart rate during the experiments, and the researchers took regular blood samples from each volunteer.
Researchers taped cotton balls laced with either lemon oil, lavender oil or distilled water below the volunteers noses for the duration of the tests.
The researchers tested volunteers ability to heal by using a standard test where tape is applied and removed repeatedly on a specific skin site. The scientists also tested volunteers reaction to pain by immersing their feet in 32-degree F water.
Lastly, volunteers were asked to fill out three standard psychological tests to gauge mood and stress three times during each session. They also were asked to record a two-minute reaction to the experience which was later analyzed to gauge positive or negative emotional-word use.
The blood samples were later analyzed for changes in several distinct biochemical markers that would signal affects on both the immune and endocrine system. Levels of both Interleukin-6 and Interleukin-10 two cytokines were checked, as were stress hormones such as cortisol, norepinephrine and other catacholomines.
While lemon oil showed a clear mood enhancement, lavender oil did not, the researchers said. Neither smell had any positive impact on any of the biochemical markers for stress, pain control or wound healing.
This is probably the most comprehensive study ever done in this area, but the human body is infinitely complex, explained Malarkey. If an individual patient uses these oils and feels better, theres no way we can prove it doesnt improve that persons health.
But we still failed to find any quantitative indication that these oils provide any physiological effect for people in general.
The wound healing ex
|Contact: Jan Kiecolt-Glaser|
Ohio State University