Ecological Momentary Intervention (E-Breathing) to Reduce Psychological Distress in Adolescents

Positive affect (PA) subscale will be calculated by averaging the PA items (items: at this moment I feel satisfied, relaxed, cheerful, energetic, enthusiastic, and calm), and a negative affect (NA) subscale will be calculated by averaging the NA items (items: at this moment I feel upset, irritated, listless/apathic, down, nervous, bored, anxious). All ratings will use a 7-point Likert scale, where 1 means not at all and 7 means very much.

This will be assessed by the Chinese version of the Beck Depression Inventory-II (BDI-II). The BDI-II is a 21-item self-report inventory designed to assess the presence and severity of depressive symptoms. Each item is rated on a 4-point Likert scale ranging from 0 to 3, based on the severity in the last two weeks. The total score ranges from 0 to 63, with higher scores indicating more severe depressive symptoms.

This will be assessed by the Chinese version of the Beck Anxiety Inventory (BAI). The BAI is a 21-item self-report questionnaire that asks about common symptoms of anxiety, such as feeling nervous, scared, and fear of dying, and was designed to distinguish anxiety symptoms from depressive symptoms. Each item is rated on a 4-point Likert scale for symptom severity in the past week, ranging from 0 (not at all) to 3 (severely). The range of total scores is from 0 to 63, with higher scores suggesting greater degrees of anxiety.

This will be assessed by the Chinese version of the Perceived Stress Scale 10-item (PSS-10). The PSS-10 is a self-report instrument that assesses global stress or how life situations are appraised as unpredictable, uncontrollable, and overloading. Respondents report the prevalence of an item within the last two weeks on a 5-point scale, ranging from 0 (never) to 4 (very often). Scoring is completed by reverse scoring four positively worded items (4, 5, 7, and 8) and summing all item scores. Scale scores range from 0-40, with higher scores indicating higher stress levels.

This will be measured by the Chinese version of the Pittsburgh Sleep Quality Index (PSQI). The index consists of a 19-item questionnaire evaluating sleep quality and disturbances over the past two weeks. The first four items are open questions, whereas items five to 19 are rated on a four-point Likert scale. Individual item scores yield seven components. A total score is obtained by adding together the seven component scores. A higher score indicates poorer sleep quality.

This will be evaluated by the Chinese version of the Cognitive and Affective Mindfulness Scale-Revised (CAMS-R). This 12-item scale measures the mindfulness experienced by individuals in four dimensions: attention, present focus, awareness, and acceptance (e.g., "It is easy for me to concentrate on what I am doing," "I am easily distracted"). All the items will be rated using a 4-point Likert scale (1 = rarely/not at all to 4 = almost always). After reversing the scores of items 2, 6, and 7, higher total scores reflect greater mindfulness qualities.

Heart rate variability (HRV) will be measured by the Polar H10 Sensor worn by some participants throughout the intervention period. Stress-response dysfunction is associated with impaired autonomic nervous system activity, as indexed by decreased HRV in stress, anxiety, and depression.