The goal of this clinical trial is to examine whether a newly developed gratitude intervention app can effectively improve psychological functioning, as measured by depression, anxiety, and stress symptoms, positive and negative affect

The main questions it aims to answer are:

1. Will people who are in the intervention group feel more positive emotions and experience fewer negative emotions such as stress, anxiety, and depression after three weeks?

Researchers will compare the intervention to a control group (a group not given the gratitude intervention) to see if the intervention works to improve psychological functioning.

Participants will:

• Complete an online survey on emotional well-being and personality traits at the beginning and end of the three-week study, with daily mood ratings and stress assessments every three days.
• Participants in the intervention group will use a mobile app to practice gratitude exercises.

Background: Gratitude interventions have been shown to decrease depression, stress and anxiety symptoms, support enhanced coping with health-related problems and might improve both psychological and physical functioning in areas. However, results have been mixed with effects varying by outcome, duration, follow-up length, format, and age. A recent meta-analysis including 27 studies focusing more specifically on symptoms of depression and anxiety suggest there is a limited effect of gratitude interventions on reducing symptoms of depression and anxiety at post-intervention and follow-up.

Objective: Thus, the present study aims to implement a three-week gratitude intervention including five different types of gratitude tasks embedded in a mobile sensing application and examine the intervention's psychological effects.

Method: Participants will be recruited and randomly allocated into the intervention and the control group. The study will measure depression, anxiety and stress symptoms, positive and negative affect, negative affectivity and social inhibition before and after the three-week intervention period as psychological variables. It will analyze the effect of the gratitude intervention on the measured variables as well as examine the impact of negative affectivity and social inhibition on depression, anxiety and stress symptoms.

Implications: If the intervention is shown to effectively reduce psychological problems, it will be tested and implemented to support the well-being of university students as a stand-alone tool.

The study will examine whether the gratitude intervention can effectively reduce depression, anxiety and stress symptoms. We intend to recruit 120 participants. Extending previous research, it will also examine whether negative affectivity and social inhibition have an impact on the measured outcomes and whether the intervention can influence these traits.

It is hypothesized that:

1. Positive affect will increase, while negative affect, stress, anxiety and depression symptoms will decrease from before to after the three weeks in the group that practices the gratitude intervention tasks (intervention group) compared to the group which doesn't (control group).
2. Negative affectivity and social inhibition will decrease from before to after the three weeks in the intervention group in comparison to the control group.

Inclusion Criteria:

• individuals aged 18-30, with access to an iPhone, and English speaking.

Exclusion Criteria:

• any self-reported cardiovascular disease; endocrine disease, kidney disease, tumor, hypertension, coarctation of the aorta, fibromuscular dysplasia, sleep apnea, which can impact the function of the cardiovascular system, as well as any current mental health treatment.

Participant data will be made available upon reasonable request to Dr. Sandra Meier (PI).