Wang 2016.

Study characteristics
Methods	Study type: RCT Design: 2‐arm, parallel group design Blinding: single blind
Participants	Sample: older adults (> 60 years), with poor sleep quality documented by PSQI scores > 7 n: 64 randomised, 64 completed and included in the analyses Age: mean 69 (SD 5.46) years Sex: 13 men, 55 women (unexplained discrepancy with total number of participants in the original report) Setting: participants' homes Country: China
Interventions	Intervention (n = 32): music group. Sleep hygiene and music listening. Participants administered the music intervention themselves. They received an MP3 player with music database stored. Music characteristics: a music database of various types of music, including Chinese instrumental classic, Western classic, natural sounds music and classical songs without lyrics. The participants could find their preferred music from this database. All selected music was soft and sedative, with stable melodies at a tempo of 60–80 bpm. Length of sessions: 30–45 minutes Frequency of sessions: daily at bedtime Duration of intervention period: 3 months Control (n = 32): sleep hygiene
Outcomes	Sleep quality (assessed with PSQI) mean (SD) at baseline and postintervention scores for components (sleep latency, sleep duration, sleep efficiency, sleep disturbance, sleep medication, daytime dysfunction, subjective sleep quality)
Notes	Trial start and end dates: October 2011 to January 2012 Funding sources: no information provided Protocol registration: none found
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Participants were assigned to the invention or control group by opening a sealed opaque envelope with a computer‐generated randomisation number indicating the group allocation" (Wang 2016, p 578–579).
Allocation concealment (selection bias)	Low risk	Comment: with this randomisation procedure, the group allocation seemed well concealed.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comment: it was not possible to blind participants to the music intervention.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "The follow‐up measurements were conducted by a research assistant, who had received training for administering PSQI and was blinded with the group allocations" (Wang 2016, p 579).
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: no attrition.
Selective reporting (reporting bias)	Low risk	Comment: protocol was not available, but there was no indication of selective reporting.
Other bias	Low risk	Comment: no indication of additional bias.

BDI: Beck Depression Inventory, range 0–63, higher scores indicate more severe depression; bpm: beats per minute
CD: compact disc; DASS‐21: Depression, Anxiety and Stress Scale, range 0–56, higher scores indicate more severe symptoms; DSM‐5: Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; EEG: electroencephalogram; GEE: generalised estimating equation; HADS: Hospital Anxiety and Depression Scale, range 0–21, higher scores indicate more anxiety or depression; ISI: Insomnia Severity Index, range 0–28, higher scores indicate more severe insomnia; MLHFQ: Minnesota Living with Heart Failure Questionnaire, range 0–105, higher scores indicate poorer quality of life; MoCA: Montreal Cognitive Assessment, range 0–30, higher scores indicate cognitive impairment; n: number of participants; PSG: polysomnography; PSQI: Pittsburgh Sleep Quality Index, range 0–21, higher scores indicate poorer sleep quality; PSS: Perceived Stress Scale, range 0–40, higher scores indicate more perceived stress; R‐MDQ: Roland‐Morris Disability Questionnaire, range 0–24, higher scores indicate more disability; RCT: randomised controlled trial; REM: rapid eye movement; SD: standard deviation; SF‐12: 12‐item Short Form Health Survey, range 0–100, higher scores indicate better physical and mental health functioning; STAI: State Trait Anxiety Inventory, range 20–80, higher scores indicate more anxiety; TAU: treatment as usual; TST: total sleep time; VAS: visual analogue scale, range 0–10, higher scores indicate more symptoms, e.g. pain; WHO: World Health Organization; WHOQOL‐BREF: World Health Organization Quality of Life Scale, range 0–100, higher scores indicate better quality of life.