This pilot randomized active-comparison study examined two formats of emotional awareness and cognitive reappraisal training for adults with co-occurring anxiety and depressive symptoms. Participants were assigned to either a real-time awareness group or a retrospective awareness group. The real-time awareness group used a smartwatch-based heart-rate prompting system to identify emotions in daily life and later complete cognitive reappraisal exercises. The retrospective awareness group completed daily evening reflection and cognitive reappraisal exercises based on emotional events from that day. The study lasted six weeks and included assessments at baseline, mid-intervention, and post-intervention. Outcomes included anxiety symptoms, depressive symptoms, emotional clarity, mood repair, cognitive reappraisal, expressive suppression, and psychological well-being. The purpose of the study was to examine preliminary patterns of change and compare how the two formats may support emotion regulation processes.

The study used a pilot randomized active-comparison design. Participants were adults aged 18 to 45 years with co-occurring anxiety and depressive symptoms. Eligible participants were randomly assigned to one of two intervention conditions: a real-time awareness condition or a retrospective awareness condition. The intervention lasted six weeks and included three assessment points: baseline/pretest, mid-intervention assessment, and post-intervention assessment.

The intervention consisted of two sequential phases. The first phase lasted approximately two weeks and focused on heart-rate baseline collection and emotional awareness training. Participants in the real-time awareness condition wore a smartwatch for three consecutive days to establish an individualized heart-rate baseline, followed by eleven days of real-time emotion identification training triggered by physiological prompts. When heart rate exceeded the individualized threshold, participants received a vibration prompt and selected the emotion category that best represented their current state. Participants in the retrospective awareness condition received no active intervention during this initial phase.

The second phase consisted of four weeks of cognitive reappraisal training for both groups. The reappraisal training was based on psychological distancing, particularly self-distancing and third-person perspective taking. During this phase, participants in the real-time awareness condition continued to receive physiological prompts and completed cognitive reappraisal exercises immediately after these prompts. Participants in the retrospective awareness condition completed daily evening reappraisal exercises based on emotionally salient events recalled from that day. Both groups attended weekly meetings with the researcher to review strategy use and discuss difficulties encountered during implementation.

Self-report outcomes were assessed at baseline, mid-intervention, and post-intervention. The study examined changes in anxiety symptoms, depressive symptoms, emotional clarity, mood repair, cognitive reappraisal, expressive suppression, and psychological well-being. The primary purpose was to characterize feasibility, preliminary effects, and temporal patterns of change associated with the two intervention formats rather than to establish definitive treatment efficacy.

Inclusion Criteria:

• Adults aged 18 to 45 years.
• Self-reported co-occurring anxiety and depressive symptoms.
• Score of 8 or above on the Chinese version of the Beck Anxiety Inventory.
• Score between 14 and 28 on the Chinese version of the Beck Depression Inventory-II.
• Ability to provide written informed consent and complete the study procedures.

Exclusion Criteria:

• Illegal substance use.
• Excessive alcohol or caffeine consumption, defined as more than four caffeinated beverages or four cans of beer per day.
• Major psychiatric disorders or cognitive impairment, such as schizophrenia or neurocognitive disorders.
• Current psychiatric medication use.
• Ongoing psychological or psychiatric treatment.
• Pregnancy or current responsibility for caring for an infant.
• Severe depressive symptoms, defined as a Beck Depression Inventory-II score of 29 or above.

De-identified individual participant data and analytic code may be available from the authors upon reasonable request, subject to ethical approval and participant confidentiality restrictions.

De-identified individual participant data and analytic code will be available after publication and for five years.

De-identified individual participant data and analytic code may be shared with qualified researchers for research purposes upon reasonable request. Requests will be reviewed by the study team and will require appropriate ethical approval, a data-sharing agreement when applicable, and compliance with participant confidentiality restrictions.