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Table 2 Summary of Findings

From: Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis

Oral magnesium supplementation for older adults with insomnia

Population: Older adults ≥55 years old with insomnia

Intervention: Oral magnesium supplementation

Comparison: Placebo

Outcome

(Duration of Follow Up)

No of Particip-ants (Studies)

Absolute Effects

(Mean Difference a ± Standard Deviation – unless otherwise specified with *)

Relati-ve Effects b

Quality of Evidence

Vote Count by Direction of Effect

Comments

  

Placebo

Magnesium Supplementation

    

Sleep Parameters

 Total sleep time (TST)

Time from sleep onset to offset (min)

(20 days to 8 weeks)

55

(2)

*The mean TST post-intervention ranged from 326.2 to 456.0 min

*The mean post-intervention TST in the intervention group was 16.06 min higher (95% CI: − 5.99 to 38.12; p = 0.15)

–

Low 1,2

Positive Effect i

 

 Sleep onset latency (SOL)

Time from wakefulness to initiation of sleep (min)

(20 days to 8 weeks)

55

(2)

*The mean SOL post-intervention ranged from 34.7 to 84.0 min

*The mean post-intervention SOL in the intervention group was − 17.36 min lower (95% CI: − 27.27 to − 7.44, p = 0.0006)

–

Low 1,2

Positive Effect

Lower numbers indicate less night-time wakefulness and better insomnia symptomology of sleep initiation

 Sleep efficiency (SE)

Sum of REM & non REM sleep / total time in bed (h)

(8 weeks)

43

(1)

MD = −  0.00 ± 0.05

MD = −  0.06 ± 0.01 h

–

Low 3

Positive Effect

 

 Early morning awakening (EMA)

Premature termination of sleep (h)

(8 weeks)

43

(1)

MD = 1.03 ± 0.02

MD = 1.01 ± 0.05

–

Low 3

Null Effect

Lower numbers indicate less early morning awakenings and better insomnia symptomology of sleep maintenance

 Slow wave sleep (SWS)

NREM stage 3 and 4 sleep (min)

(20 days)

12

(1)

MD = + 10.1 ± 15.4

MD = + 16.5 ± 20.4

–

Very Low 1,2,4

Positive Effect

SWS, or deep sleep, is purported to be more restorative sleep.

Sleep Questionnaires

 Insomnia Severity Index

Score from 0 to 28; ≥ 15 = clinical insomnia

(8 weeks)

43

(1)

MD = −  0.5 ± 1.71

MD = −  2.38 ± 2.24

–

Low 3

Positive Effect

Lower scores indicate better sleep quality.

 PSQI

Score from 0 to 21; ≥ 5 = poor sleeper

(8 weeks)

96

(1)

MD = −  4.1

See comment

MD = −  3.4

See comment

–

Low 5

Null Effect ii

No numerical confidence intervals were reported but available in Figure form.

Adverse Events

 No data

See comment

–

–

–

–

–

–

None of the studies reported adverse events

  1. a – All mean differences (MD) are within group change from baseline mean differences unless otherwise specified with *. The * mean differences are between group post-intervention/treatment mean differences
  2. b – No dichotomized outcomes were reported in any of the studies
  3. Acronyms: h Hour; min Minute; nREM Non rapid eye movement; REM Rapid eye movement
  4. GRADE Working Group grades of evidence
  5. High certainty = very confident that the true effect lies close to that of the estimate of the effect
  6. Moderate certainty = moderately confident that the true effect lies close to that of the estimate of the effect
  7. Low certainty = limited confidence in the effect estimate, the true effect may be substantially different from the estimate of effect
  8. Very Low certainty = very little confidence in the effect estimate, the true effect is likely to be substantially different from the estimate of effect
  9. 1 – Serious or concerning methodological limitations were detected in all studies, especially poor internal validity in the randomization process and bias arising from deviations from intended outcomes. Downgrade one level for risk of bias
  10. 2 – Only two studies included, with wide confidence intervals and total sample size of 55. Downgrade one level for imprecision
  11. 3 – Only one study included. Some concerns for risk of bias in the randomization process and bias arising from deviations from intended outcomes (same as above) mainly due to poor reporting. Downgraded one level. Total sample size of 43. Downgraded one level for imprecision. (Total: 2 levels downgraded)
  12. 4 –SWS is a surrogate outcome for insomnia symptoms, the main outcome assessed in the review question. While there is biological plausibility that SWS may help with restorative sleep, there is limited evidence in SWS to improvement in insomnia symptoms. Downgraded one level for indirectness of evidence
  13. 5 – Only one study included. High risk of bias from selective reporting. Downgrade one level. Total sample size of 96. Downgraded one level for imprecision
  14. Voting by Direction of Effect
  15. i – Despite lack of statistical significance in the meta-analysis, vote counting was conducted purely by observed direction of effect alone
  16. ii – Each question of the PSQI is scored 0, 1,2 or 3. Thus, a difference of less than 1 is categorized as a null effect
  17. Reference: Schünemann HJ, Higgins JPT, Vist GE, Glasziou P, Akl EA, Skoetz N, Guyatt GH. 2019. Chapter 14: completing ‘summary of findings’ tables and grading the certainty of the evidence. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane handbook for systematic reviews of interventions version 6.0 (updated July 2019). Cochrane. Available from
  18. www.training.cochrane.org/handbook (http://www.training.cochrane.org/handbook)
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BMC Complementary Medicine and Therapies

ISSN: 2662-7671

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