Peppermint

Sahar Hamzeh et al. (2020) · Evidence-based complementary and alternative medicine : eCAM

This randomized controlled trial with 120 adult cancer patients explored whether breathing in lavender or peppermint essential oil before bed could ease the poor sleep that affects roughly a third of people with cancer. Sleep disruption in cancer care is often treated with sedative medications, which carry dependency risks, so researchers wanted a gentler alternative. Aromatherapy works through inhalation: aromatic molecules bind receptors in the nasal lining, sending signals to brain regions (the limbic system and thalamus) that release calming compounds like serotonin. Lavenders calming compounds are linalool and linalyl acetate; peppermints main compound, menthol, is thought to ease anxiety by damping stress-hormone release. Patients (average age 49, just over half women, most being treated for leukemia) at an oncology ward in Kermanshah, Iran were split into three equal groups of 40. For seven nights, the lavender and peppermint groups had three drops of their essential oil placed on a cotton ball pinned near the collar for 20 minutes before sleep; a masked control group got scented water instead. Everyone completed the Pittsburgh Sleep Quality Index (PSQI), a validated sleep questionnaire, before starting and again after the week was up. All participants started with poor sleep (average PSQI score of 12.62, where 5 or higher signals a problem). Sleep quality improved across all three groups over the week (p < 0.0001 for the change over time), and the pattern of improvement differed by group (interaction p < 0.001): 10% of patients using either lavender or peppermint reached good sleep quality by the end, versus 5% on the control. Even so, none of the direct group-to-group comparisons reached statistical significance -- lavender vs. control (p = 0.28), peppermint vs. control (p = 0.19), and lavender vs. peppermint (p = 0.82) -- meaning the trial could not statistically confirm that either oil outperformed the masked control, even though both intervention groups trended toward greater improvement. No adverse effects were reported from either oil. These results offer tentative, not definitive, support for lavender or peppermint inhalation as a low-cost, low-risk sleep aid alongside cancer care -- the trend favored both oils, but the comparison against a masked control did not reach statistical significance. Limitations include a study population with mixed cancer types and stages, unaccounted-for concurrent medications, and no report of cancer stage for many patients, all of which could affect sleep quality and treatment response. Larger trials with stage-matched groups and a truly unscented control are needed to determine whether either essential oil offers real benefit.