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The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial
Double-blind RCT (n=46 older adults) of 500 mg/day magnesium versus placebo for 8 weeks reporting statistically significant improvements in insomnia severity index, sleep-onset latency, sleep efficiency, and sleep time alongside melatonin/renin/cortisol shifts.
Design
Parallel-group 8-week trial; 500 mg/day oral magnesium vs placebo; ISI, sleep diary, and blood draws for serum magnesium, renin, melatonin, cortisol.
Headline between-group signals (per abstract)
- ISI score: lower with magnesium (p = 0.006)
- Sleep-onset latency: shorter (p = 0.02)
- Sleep efficiency: higher (p = 0.03)
- Sleep time: increased (p = 0.002)
- Serum melatonin / renin: higher on magnesium; serum cortisol: lower (p values < 0.01 for renin; 0.007 melatonin; 0.008 cortisol)
Caveats
Single modest-sized cohort; dietary confounds logged but elderly primary insomnia remains heterogeneous (consider OSA, depression, nocturia in real practice).
Outcomes
- Insomnia SeverityRCT: Insomnia Severity Index favored magnesium vs placebo (p = 0.006); see primary tables for absolute point changes
- Sleep Onset LatencyRCT: sleep-onset latency shorter with magnesium vs placebo (p = 0.02); read paper for diary-derived minute estimates
- Sleep EfficiencyRCT: sleep efficiency higher with magnesium vs placebo (p = 0.03)
- Total Sleep TimeRCT: sleep time increased with magnesium vs placebo (p = 0.002)