Dietary Supplement Interventions and Sleep Quality Improvement: A Systematic Review and Meta-Analysis.

Dietary supplement interventions significantly reduced Pittsburgh Sleep Quality Index (PSQI) scores compared to control conditions.

• MD: -0.70, 95% CI: -1.37 to -0.03, p < 0.05
• Lower PSQI scores indicate better sleep quality
• Analysis based on 28 randomized controlled trials
• Databases searched included PubMed, Web of Science, CNKI, ScienceDirect, Wiley, and CVIP

Dietary supplement interventions significantly increased sleep efficiency (SE).

• Increase of +2.58 minutes, 95% CI: 2.01–3.16, p < 0.00001
• This was the most statistically significant finding among sleep metrics reported
• Analysis included populations with sleep disorders and healthy individuals

Dietary supplement interventions significantly prolonged total sleep time (TST).

• SMD: +0.23, 95% CI: 0.04–0.43, p < 0.05
• Standardized mean difference (SMD) was used, suggesting pooling across studies with different measurement units
• Effect size was relatively small but statistically significant

Dietary supplement interventions significantly shortened sleep latency (SL).

• SMD: -0.24, 95% CI: -0.37 to -0.10, p < 0.001
• Negative SMD indicates reduced time to fall asleep
• Specific supplements identified as contributing to SL reduction included tryptophan, vitamin D, omega-3, zinc, and antioxidants

Dietary supplement interventions significantly reduced wake after sleep onset (WASO).

• SMD: -0.30, 95% CI: -0.48 to -0.12, p < 0.001
• Negative SMD indicates less time spent awake after initially falling asleep
• Effect size of -0.30 was the largest SMD observed among the sleep continuity measures

Number of awakenings after sleep onset (NASO) showed only a marginal, non-significant reduction with dietary supplement interventions.

• MD: -1.57, 95% CI: -3.16 to 0.02, p = 0.05
• The confidence interval just crossed zero, indicating the result was not statistically significant at conventional thresholds
• This was the only sleep outcome measure that did not reach statistical significance

The systematic review and meta-analysis included 28 randomized controlled trials examining dietary supplement interventions on sleep quality.

• Six databases were searched: PubMed, Web of Science, CNKI, ScienceDirect, Wiley, and CVIP
• Sleep evaluation metrics included PSQI, SE, SL, TST, WASO, and NASO
• Heterogeneity was quantified via I² statistics
• Meta-analysis procedures were executed in Review Manager 5.3 and Stata 17.0
• Both populations with sleep disorders and healthy individuals were included

Specific dietary supplements identified as potentially enhancing sleep quality include tryptophan, vitamin D, omega-3, zinc, and antioxidants.

• These supplements were associated with decreasing sleep latency and wake after sleep onset, increasing sleep efficiency, and extending total sleep time
• The mechanisms by which each supplement acts were described as distinct (e.g., 'respectively')
• These findings were drawn from subgroup or narrative analyses within the broader meta-analysis