Table 1.

PICOS criteria and eligibility used in this review

Domain	Criteria
Population	Adults or adolescents; healthy volunteers or individuals with anxiety, insomnia/sleep disturbance, mild OSA/snoring
Intervention	Wind instrument training/breath-controlled sound production (e.g., didgeridoo, harmonica, flute, clarinet/saxophone/oboe/bassoon and trumpet); structured lessons, supervised practice or standardised home programs
Comparator	Inactive/usual care; mindful breathing; passive listening/white noise; within-subject baseline
Outcomes	Anxiety scales; sleep measures (subjective sleep quality, sleep-onset latency, awakenings, PSG indices incl. AHI/snoring); autonomic indices (HRV/RSA, heart rate, respiratory rate); feasibility/adherence
Study design	Randomised or non-randomised controlled trials; crossover trials; pre–post interventional human studies; mechanistic human laboratory studies
Exclusion	Non-human studies; n < 5 case reports; editorials/reviews/theory only; passive listening only (no active sound production); non-wind interventions (e.g., strings/keyboard only); insufficient outcome reporting

Note (scope): Eligibility targets active, breath-driven sound; background/mechanistic sources cited elsewhere are not counted in the evidence set; Abbreviations: AHI, apnoea–hypopnoea index; HRV, heart-rate variability; OSA, obstructive sleep apnoea; PSG, polysomnography; RSA, respiratory sinus arrhythmia.