Effects of Transcutaneous Auricular Vagus Nerve Stimulation on Perceived Stress and Psychological Distress in University Students With High Distress Levels: A Randomized Blinded Clinical Trial

Mental health is increasingly recognized as a core component of overall health, reflecting the capacity to regulate behavior, maintain daily functioning, and sustain satisfying interpersonal relationships. Chronic exposure to adverse circumstances, particularly prolonged stress, has been associated with mental health problems and contributes to the onset and maintenance of common psychological disorders.

University students are exposed to multiple risk stressors (psychological, academic, biological, lifestyle, social, and economic) associated with poorer well-being. The transition to higher education often coincides with entry into adulthood and is frequently described as a particularly demanding period in emotional and mental terms. Students commonly report high stress while adapting to academic demands that may exceed previously acquired skills and coping strategies. Stressors in this setting often include academic pressure, peer competition, ineffective time management, financial concerns, work-life conflicts, and mental overload from multiple responsibilities.

Sustained exposure to these stressors is associated with poorer learning performance, physical health problems, and sleep disturbances. High and persistent stress, especially when perceived as uncontrollable and excessive, is frequently associated with higher psychological distress among university students. In turn, psychological distress is associated with elevated anxiety and depressive symptoms, sleep problems, reduced self-esteem and self-efficacy, and in more severe presentations, with self-injury, suicidal ideation, substance use, and neglect of academic responsibilities.

International literature has reported high burden and, in some settings, worsening trends in university student mental health over the last decade, positioning it as a relevant public health concern. In the WHO World Mental Health International College Student Initiative, 93.7% of 20,842 students across 24 universities in nine countries experienced some level of stress. In Portugal, similar concerning patterns have been reported: at the University of Lisbon, one quarter of 7,756 students presented severe or very severe stress levels, and a further survey indicated that nearly half of 2,084 students reported psychological symptoms and about one quarter had considered suicide.

Multiple approaches have been used to address stress-related mental health problems in university students, including psychotropic medication, cognitive-behavioral therapy, mindfulness-based interventions, relaxation techniques, and biofeedback-based strategies. However, pharmacological approaches may be limited by side effects and other constraints, and many effective interventions require time, staffing, or infrastructure that can restrict scalability in academic settings. These limitations underscore the need to evaluate complementary interventions that are feasible, acceptable, and implementable in university contexts.