2015 Volume 16 Issue 1 Pages 7-14
A randomized crossover trial was performed to examine the effect of essential oils on numerical ability and mood in elementary school students. Participants were 38 healthy students attending sixth grade (11–12 years of age). The students were randomly assigned to two groups: one group was tested with peppermint oil and the other group was tested with sweet orange oil. A crossover experimental procedure was conducted using purified water as a control after a washout period to remove the effect of the previous procedures. Mood change was evaluated using a two-dimensional mood scale short term (TDMS-ST) and visual analog scale (VAS); numerical ability was assessed based on the number of single-digit additions attempted on a 100 squares calculation grid in 10 minutes, as well as the number of incorrect responses. Finally, the ability to access vocabulary was evaluated using verbal fluency tasks. Olfactory stimulation with essential oil inhalation for 30 seconds, followed by continuous exposure with the scented plate on the table was performed. VAS scores for concentration, feeling refreshed, and energy showed a significant increase with peppermint oil compared to purified water. A comparison of VAS scores for sweet orange oil with those for purified water showed significant increases for absence of irritation, motivation, absence of anxiety, vigor, and feeling refreshed. There were significant increases in the TDMS-ST for vitality level, stability level, and pleasure level with the sweet orange oil. There were no significant differences in the 100 squares calculation between peppermint oil, sweet orange oil, and purified water. However, the mean number of incorrect responses for peppermint oil was 3.2 compared to 4.2 for purified water (a 24% decrease); for sweet orange oil, the mean number of incorrect responses was 3.2 compared to 4.4 for purified water (a 27% decrease). However, there were no significant differences. Furthermore, there were no significant differences in the verbal fluency tasks between peppermint oil, sweet orange oil, and purified water. These results suggest that peppermint oil and sweet orange oil affect mood in elementary school students by leaving them refreshed, and may affect numerical ability.
