Essential Oil-enhanced digital hypnotherapy for subclinical generalized anxiety: a study protocol for a randomized controlled trial

Background: Subsyndromal generalized anxiety is highly prevalent and associated with impaired well-being, elevated stress, and functional limitations, yet affected individuals often do not meet criteria for guideline-based treatment. Scalable, low-threshold digital interventions that target psychophysiological regulation may help address this gap. Guided self-hypnosis and aromatherapy using essential oils have each demonstrated anxiolytic and relaxation-promoting effects. Combining these approaches may enhance efficacy and allow for conditioning of relaxation responses via olfactory cues. Methods: = 630 participants will be randomized into six groups. Four groups enter the primary efficacy analysis: (1) self-hypnosis + bergamot essential oil, (2) self-hypnosis + lavender essential oil, (3) self-hypnosis without essential oil, and (4) a minimal-intervention control. The intervention is delivered online over six weeks (Phase 1), followed by a two-week conditioning phase without hypnosis (Phase 2), in which stimulus-specific effects of the essential oils are tested. The primary outcome is subjective relaxation, measured by the Multidimensional Mood Questionnaire (MDBF) at baseline, post-intervention (6 weeks), and post-conditioning (8 weeks). Secondary outcomes include anxiety symptoms, perceived stress, sleep quality, well-being, and worry. In a voluntary subsample, heart rate variability (HRV) and pulse wave variability (PWV) will be assessed as physiological correlates of relaxation. In addition, the questionnaires are expanded to include open-ended questions, enabling an exploratory assessment of participants' experiences, attitudes, and reflections on the intervention and its potential for sustainability. This approach complements quantitative results with qualitative insights and may reveal new perspectives for future research. Discussion: https://www.drks.de/search/de/trial/DRKS00039047/details, Identifier DRKS00039047.