Daily 3-Minute Laughter Practice (Laughie Prescription)"

Control group The control group will not take part in the Laughie Prescription

The intervention will consist of 3-minutes of laughter (joyful and natural laughter is recommended) per day. Each day participants will laugh for one minute in a group (virtual and/or actual) guided by a professional laughter practitioner who is not going to be involved in the analysis of the data. That laughter will be recorded. The recording (the "Laughie") will then be prescribed for participants to laugh with (with others - family, friends, colleagues, or alone) twice a day. This will result in 3 minutes of laughter per day (the first in a group, the second two prompted by the Laughie)

The WHO-5 Well-being Index (WHO-5; World Health Organization, 1998), a widely used and validated measure, was administered pre- and post-intervention as a self-report well-being measure. Eser et al. validated and established the reliability of the WHO-5 Turkish scale in their 2019 study. Based on guidance from Eser et al. (2019), the WHO-5 Turkish scale could be used without seeking explicit permission, provided it was cited appropriately. The scale consists of five items (e.g. 'In the last 2 weeks, I have felt cheerful and in good spirits') rated on a 6-point Likert scale grading; At no time = 0, some of the time = 1, less than half of time = 2, more than half of time = 3, most of the time = 4, all of the time = 5. The scoring of the scale is done by summing the score obtained from each item, and the highest score that can be obtained from the scale is 25 and the lowest score is 0.

The Oxford Happiness Questionnaire (OHQ-8) is an abbreviated version of the OHQ-29. It was developed to measure personal happiness and subjective well-being. The original OHQ-29 followed the format of the Beck Depression Inventory, with 20 items reversed and nine additional items added to cover aspects of happiness. The OHQ-29 is a single-scale questionnaire that can be answered on a standard six-point Likert scale. Almost half of the items (14) are negatively worded to reduce respondent bias.

The National Stressful Events Survey for PTSD Short Scale (NSESSS-PTSD) was used to assess PTSD symptoms. This scale is a 9-item assessment of the dimensions of post-traumatic stress disorder by DSM-5 criteria. Participants rate each item on a five-point Likert scale ranging from 0 ('never') to 4 ('always'). The total score ranges from 0 to 36, with higher scores indicating more severe symptoms of PTSD. The Turkish version of the PTSD short scale is a valid and reliable measure (alpha = 0.87) for the assessment of PTSD symptoms in the Turkish population.