PI moving to another university--study will not be done at UK; Coronavirus pandemic will likely delay start at University of Texas at Arlington

The study is designed to examine the efficacy of a mobile application heart rate variability biofeedback exercise on heart rate variability and depression.

The main objective of this study is to assess the Breather app manufactured by Happify, Inc., as a tool for improving levels of depression and heart rate variability in college students.Happify™ Breather is a mobile app that provides users with HRV biofeedback aimed at improving mental health and wellness. Breather uses HRV sensors to help users control breathing, leading to calm and relaxation. The more relaxed users are, the more visually reinforcing scene elements will appear in the underwater environment of the game. Breather uses an optical sensor in a smartphone camera. During app use, users are cued by the app to breathe at 6 cycles/minute using a breath pacer. When the smartphone camera flash is illuminated, color signal changes are measured from the fingertip pressed to the camera lens.

The study population is college students who score in the clinical range on the PHQ-9. Secondary outcomes include anxiety, somatoform symptoms, and app adherence.

Although traditionally considered a healthy group, concern is mounting about the health and mental health of college students (Hunt & Eisenberg, 2010). Mental health problems, such as depression, often go untreated in young college-age adults (Saeb et al., 2015). Depression is associated with poor health outcomes (Rutter et al., 2013). Suicide, often associated with depression, is a leading cause of death in college students (Drapeau & McIntosh, 2015). Research suggests that stress-related interventions would be useful for college students at risk of poor mental health outcomes (Karatekin, 2017); however less is known about the impact of mobile health interventions on depression in college students.

Studies have shown that heart rate variability (HRV), a potent all-cause morbidity and mortality indicator, is reduced in persons with depressive disorders (Kemp, Quintana, Felmingham, Matthews, & Jelinek, 2012). Although HRV is typically higher in college-age students because they are often younger, studies have shown that college students HRV biofeedback involves voluntary changes in breathing rate, rhythm, pattern, and quality. Within a few minutes of rhythmic stimulation of the cardiovascular system through slow paced breathing at around six breaths per minute, HRV biofeedback produces robust increases in HRV (Vaschillo, Vaschillo, & Lehrer, 2006). Emotional regulation, to include depressive symptoms, can be improved through HRV biofeedback (Henriques, Keffer, Abrahamson, & Horst, 2011; Siepmann, Aykac, Unterdörfer, Petrowski, & Mueck-Weymann, 2008).

Smart phones offer an expedient way to deliver digital interventions that promote relaxation and improve mood. Happify™ Breather is a mobile app that provides users with HRV biofeedback aimed at improving mental health and wellness. Breather uses HRV sensors to help users control breathing, leading to calm and relaxation. The more relaxed users are, the more visually reinforcing scene elements will appear in the underwater environment of the game. Breather uses an optical sensor in a smartphone camera. During app use, users are cued by the app to breathe at 6 cycles/min using a breath pacer. When the smartphone camera flash is illuminated, red color signal changes (increasing with systole and decreasing with diastole) are measured from the fingertip pressed to the camera lens and sampled at 50 Hz. In a validation study, results obtained from the Happify™ HRV biofeedback Breather app were consistent with Holter monitor results (Stein, 2018). The app is free of charge and publicly available on the iTunes App Store.

The primary objective of the study is to examine the efficacy of the Happify™ Breather app's biofeedback exercise in improving high frequency (HF) heart rate variability (HRV) measures and depression scores in students compared to control. Secondary outcomes are to test the efficacy of the app for anxiety and somatoform symptoms, as well as adherence to the app.

Inclusion Criteria:

• Age 18-45;
• University of Kentucky college student;
• Self-reported low mood;
• Own a smart phone or iPod (6th Generation or later).

Exclusion Criteria:

• Score >/= 10 on the PHQ-9 measure from the PHQ-SADS;
• Self-reported diagnosis of lung disease (e.g., Chronic Obstructive Pulmonary - Disease. Asthma requiring medication), coronary heart disease, stroke, or uncontrolled diabetes (HA1c>7.0);
• Self-reported history or diagnosis of seizure disorder;
• Self-reported prescription for tricyclic antidepressants and/or clozapine
• Current smoking or vaping (use in last 30 days);
• Previous participation in an HRV biofeedback study