This randomized controlled pilot trial investigates the effects of a brief workplace mindfulness-based intervention (MBI) on mood among full-time employees in Japan. Twenty-five participants are randomly assigned to either the MBI group or a wait-list control group. The MBI group receives three 90-minute workshops spaced four weeks apart, along with daily home mindfulness practice. Mood is assessed monthly over three months using the Japanese version of the Profile of Mood States 2 (POMS2). The primary outcome is Total Mood Disturbance (TMD). This study is approved by the Ryusei Hospital Institutional Review Board and conducted as a feasibility trial.

This pilot randomized controlled trial aims to evaluate the month-by-month effects of a low-intensity workplace mindfulness-based intervention (MBI) on mood among full-time employees in a healthcare setting in Okinawa, Japan. Participants are assigned in a 1:1 ratio to either the MBI group or a wait-list control group. The intervention consists of three 90-minute in-person workshops delivered at monthly intervals, incorporating psychoeducation, guided stretching, and focused-attention meditation. Participants in the MBI arm are also encouraged to practice mindfulness at home for 10 minutes per day. Mood is assessed at baseline and monthly over three months using the Japanese POMS2 Short Form. The primary endpoint is change in Total Mood Disturbance (TMD); secondary outcomes include fatigue (measured via a visual analogue scale) and presenteeism (measured via Single-Item Presenteeism Question, the University of Tokyo single-item edition (SPQ) ). Linear mixed-effects models are used for statistical analysis. The study is approved by the Ryusei Hospital Institutional Review Board (Approval No. 2024-02) and conducted as a feasibility study without prospective registration.

Inclusion Criteria:

• Full-time employment
• Age 20 years or older
• Provided written informed consent

Exclusion Criteria:

• Current or past psychiatric disorder
• Any medical condition deemed incompatible with study participation

Deidentified individual participant data (IPD) underlying the primary and secondary outcome measures will be shared.

IPD and supporting documents will be available beginning 6 months after publication of the results and will remain available for 36 months.

Qualified researchers with a methodologically sound proposal may request access to the data. Requests will be reviewed by the study team. A data use agreement will be required prior to data sharing.