The identification of the effects of natural fragrance on physiological responses and craving for short-form video viewing in university students

INTERVENTION: Others : This study employs a within‐subject cross‐over design in which every participant experiences both (1) the natural fragrance (fir essential oil) inhalation condition and (2) the odorless (control) condition. The order of the two conditions (fragrance first or odorless first) is randomly counterbalanced across participants, and a 5‐minute rest (wash‐out) period is placed between the two conditions to prevent carry‐over effects from the preceding condition. The content of each condition is as follows. In the fragrance inhalation condition, the participant rests with eyes closed for 3 minutes, watches YouTube short‐form videos for 10 minutes, and immediately after viewing, inhales the fragrance of an essential oil extracted from fir needles by steam distillation for 3 minutes. The fragrance is diffused through an electronic diffuser placed 1 to 2 meters away from the participant, and the concentration is set with reference to a previous study (38 microliters per 22.68 cubic meters of space) and adjusted through a pilot test so that the scent is perceived as subtle. In the odorless condition, the procedures of rest (3 minutes) and short‐form video viewing (10 minutes) are identical to the fragrance condition, but for the 3 minutes immediately after viewing, the participant remains in the same environment while no fragrance substance is released from the diffuser. In other words, the only difference between the two conditions is whether the fir essential oil fragrance is provided. The measurement timepoints are as follows. Physiological responses (brain activity measured by functional near‐infrared spectroscopy and autonomic nervous system activity measured by heart rate variability) are measured continuously in both conditions, from the attachment of the measurement devices until the end of the experiment, and in the analysis, the rest period, the short‐form video viewing period, and the inhalation period (fragrance/odorless) are compared. The degree of craving for short‐form video viewing is assessed with a self‐report questionnaire for 1 minute immediately after the inhalation in each condition. CONDITION: Not Applicable PRIMARY OUTCOME: Brain activity (changes in oxygenated hemoglobin concentrations in the prefrontal cortex measured by functional near‐infrared spectroscopy) Degree of craving for short‐form video viewing (self‐report scale modified from the Korean version of the craving questionnaire for the purpose of this study, 7‐point Likert scale) Heart rate variability (indicators of autonomic nervous system activity: high frequency component and low frequency/high frequency ratio), HR SECONDARY OUTCOME: Differences in the effects of fragrance inhalation according to individual characteristics (comparison by individual characteristics using the internet/game/smartphone overdependence screening tool, the nature relatedness scale, and the quality of life scale) INCLUSION CRITERIA: ‐ University students 20 years or older in Korean age (18 years or older in international age) ‐ Individuals who understand the purpose of the study and have voluntarily submitted written informed consent to participate