Children's Laughter and Fun Yoga as Adjunctive Pain Relief Following Chemotherapy.

Daily pain will be measured using the Wong-Baker FACES Pain Rating Scale (0, 2, 4, 6, 8, 10) at a fixed evening window (17:00-20:00) on Days 0-6 to characterize the day-by-day trajectory of pain during the dexamethasone period. At each assessment, a standardized script will be read by the parent under researcher guidance, and the child will select the face that best represents their pain "right now." If no clear response is given, the script may be repeated once without prompting toward any choice. Scores will be recorded immediately on the CRF with date and time. This outcome provides a daily series of FPS-R values across the 7-day observation window, enabling description of within-week pain patterns and comparison of peak timing and magnitude between groups, complementary to the primary endpoint (Day 5-6 average).

Opioid analgesic use will be assessed during the dexamethasone and chemotherapy period, as non-opioid analgesics are not routinely used during this phase. Opioid exposure will be measured by converting all administered opioid doses to oral morphine milligram equivalents (MME), including cumulative 6-day MME and weight-adjusted MME per kilogram. Additional measures include time from chemotherapy and dexamethasone administration to first rescue opioid dose, number of rescue opioid doses, and the proportion of participants requiring any opioid analgesia. Emergency department visits for pain control during the study period will also be recorded, including opioid administration and disposition when applicable.

Depressive symptoms will be assessed using the Arabic Short Mood and Feelings Questionnaire - Parent version (SMFQ-P), a 13-item parent-reported questionnaire that evaluates core depressive symptoms such as sadness, loss of interest, irritability, fatigue, guilt, and low self-esteem. Each item is rated on a 3-point scale ("not true," "sometimes true," "true"), with total scores ranging from 0 to 26; higher scores indicate greater depressive symptom severity. The Arabic SMFQ-P has been validated in Lebanon and is appropriate for use in research settings. The questionnaire will be administered to parents at baseline (Day 0) and at the end of the intervention period (Day 6). For younger children, the tool will be completed as a parent-proxy measure focusing on observable mood and behavior.

The SCARED-5 (5-item Screen for Child Anxiety Related Emotional Disorders) is a brief parent-report screening tool used for youth anxiety. Although an Arabic validation of the short version is not yet available, the full Arabic SCARED-P (41-item parent version) has demonstrated excellent psychometric properties in Lebanon (a = 0.92, convergent validity with SDQ Emotional, discriminant validity). The SCARED-5 has undergone a recent psychometric evaluation, showing strong internal consistency, single-factor structure, good correlation with the full scale, and a suggested cutoff score of ≥ 2 for identifying anxiety. Based on this evidence, we will use the Arabic version of the items from the validated full SCARED-P, structured as the SCARED-5, and apply a clinical alert threshold of ≥ 2. In younger children (age <6), scores will be treated as exploratory and interpreted with caution.

Sleep will be assessed using the Arabic Sleep Disturbance Scale for Children (SDSC), a 26-item parent-reported questionnaire that evaluates common pediatric sleep problems, including difficulties with sleep initiation and maintenance, breathing-related sleep disturbances, arousal disorders, excessive daytime sleepiness, and sleep-wake transition problems. Each item is rated on a 5-point scale, with higher total scores indicating greater sleep disturbance. The SDSC will be administered at baseline (Day 0) and at the end of the intervention period (Day 6). The primary sleep outcome is the change in total SDSC score from baseline to Day 6. For younger children, results will be exploratory. Participants with markedly elevated scores will be flagged and referred to the treating physician for clinical follow-up.