The effect of magnesium supplementation on primary insomnia in elderly: a double blind placebo-controlled clinical trial

Nearly 50% of older adults have insomnia, with difficulty getting to sleep, early awakening or feeling un-refreshed on waking. With aging, several changes occur that can place one at risk for insomnia including age-related changes in various circadian rhythms, environmental and lifestyle changes and decreased nutrients intake, absorption, retention and utilization. The natural NMDA antagonist and GABA agonist, Mg2+ seams to play a key role in the regulation of sleep. The objective of this study was to determine the efficacy of magnesium supplementation to improve insomnia in elderly. A double blind randomized clinical trial was conducted in 46 elderly subjects, randomly allocated into the magnesium or the placebo group and received 500 mg magnesium or placebo daily for 8 weeks. Questionnaires of insomnia severity index, physical activity, and sleep-log were completed at baseline and after the intervention period. Anthropometric confounding factors, daily intake of magnesium, calcium, potassium, caffeine, calories form carbohydrates and total calorie intake, were obtained using 24-hrs recall for 3-days. Blood samples were taken at baseline and after the intervention period for analysis of serum magnesium, renin, melatonin and cortisol. Statistical analyses were performed using SPSS19 and P-values < 0.05 were considered as statistically significant. No significant differences were observed in assessed variables between the two groups at the baseline. As compared to the placebo group, in the experimental group, dietary magnesium supplementation brought about statistically significant increases in sleep time (P = 0.002), sleep efficiency (P = 0.03), concentration of serum renin (P < 0.001) and melatonin (P = 0.007), also resulted in significant decrease of ISI score (P = 0.006), sleep onset latency (P = 0.02) and serum cortisol concentration (P = 0.008). Supplementation also resulted in marginally between-group significant reduction in early morning awakening (P = 0.08) and serum magnesium concentration (P = 0.06). Although total sleep time (P = 0.37) did not show any significant between-group differences. Supplementation of magnesium appears to improve subjective measures of insomnia such as ISI score, sleep efficiency, sleep time and sleep onset latency, early morning awakening and likewise insomnia objective measures as concentration of serum renin, melatonin and serum cortisol, in elderly people.