Effect of Hemerocallis essence aroma on brain activity and sleep processes via scalp electroencephalogram

Sleep disorders are widespread. Inhaled aromatherapy has shown advantages over medication in treating insomnia. Daylily (Hemerocallis fulva) has been found to positively affect sleep either by ingestion or inhalation, but there is a lack of research on the sleep aid effect of its inhalation route. At present, the floral scent characteristics of daylily are not obvious, and the extraction rate of essential oil is low. Based on the above problems, this study developed daylily essence which replicates the natural aroma of plants and investigated the effect of inhaling daylily essence aroma on sleep activity by using Pittsburgh Sleep Quality Index (PSQI) and electroencephalogram (EEG). According to PSQI results, inhaling the aroma of daylily essence improved participants' subjective sleep quality. The difference between men and women was statistically significant (p < .05). The slow-wave sleep activity of EEG in the experimental group was significantly stronger than that in the control group (p < .01). In addition, the frontal and central regions were more responsive to aroma stimuli (p < .05). The results of this study show that the aroma of daylily can promote the subjective and objective sleep quality of healthy college students, and the use of fragrance intervention is a potential scheme to improve sleep quality and insomnia.