. 2021 Apr 17;21:125. doi: 10.1186/s12906-021-03297-z

Table 1.

Characteristics of included studies

Study (Ref #)	Country	Methods (Design)	Participants (Mean Age) (Diagnosis Method)	Participant Inclusion Characteristics (Exclusion Criteria)	Intervention ^a (Duration)	Compari-son	Outcomes ^b	Adverse Effects Reported?
Abbasi et al. 2012 [24]	Iran	RCT (Parallel)	46 elderly volunteers (65) (ISI)	Adults 60–75 years old with insomnia according to ISI and sleep-log questionnaires (BMI < 25 or > 34.9, dietary intake Mg > 75% RDA, serum Mg > 0.95 mmol/L, use of loop diuretics, cyclosporine, digoxin, amphotericin, hormonal treatment, renal disease, heart failure or sleep related movement or respiratory disease, psychiatric disorder, substance abuse, major life stressor, trans meridian flight in last 6 weeks)	500 mg elemental Mg daily Administered as 414 mg MgO PO BID (8 weeks)	Placebo	- ISI * - Sleep log * - Physical activity log - Food diary - Blood samples (Mg, cortisol, renin, melatonin)	No
Held et al. 2002 [25]	Germany	RCT (Cross-over)	12 healthy volunteers (69) (Sleep EEG)	Healthy older adults aged 60–80 years (Psychiatric disorders, cognitive impairment, recent stressful event, substance abuse, trans meridian flight in last 3 months, shift work, medical illness, aberrations in blood chemistry/EEG/ECG, sleep related respiratory or movement disorder)	729 mg elemental Mg daily Administered as an up-titration of 403 mg MgO PO daily × 3 days, 403 mg MgO BID × 3 days, and 403 mg MgO PO TID × 14 days (Treatment intervals of 20 days duration separated by 2 weeks washout)	Placebo	- Sleep EEG * - Blood samples (ACTH, cortisol, renin, AVP, ATII, aldosterone) ^c	Yes (voluntary report)
Nielsen et al. 2010 [26]	United States of America	RCT (parallel)	100 older adults (59) (PSQI)	Adults > 51 years with global PSQI score > 5 indicating poor sleep quality (BMI > 40, respiratory tract disease, COPD, use of O2 or CPAP, use of ACEi, Mg-retaining or potassium sparing drugs)	320 mg elemental Mg daily Administered as 320 mg Mg citrate PO two tablets each morning and evening and one tablet at noon (8 weeks)	Placebo	- PSQI * - Food diary - Blood samples (Mg, erythrocyte Mg, calcium) - Urine samples (Mg, calcium, citrate)	No

Study (Ref #)

Country

Methods
(Design)

Participants
(Mean Age)
(Diagnosis Method)

Participant Inclusion Characteristics (Exclusion Criteria)

Intervention ^a
(Duration)

Compari-son

Outcomes ^b

Adverse Effects Reported?

Abbasi et al. 2012

[24]

Iran

RCT (Parallel)

46 elderly volunteers

(65)

(ISI)

Adults 60–75 years old with insomnia according to ISI and sleep-log questionnaires

(BMI < 25 or > 34.9, dietary intake Mg > 75% RDA, serum Mg > 0.95 mmol/L, use of loop diuretics, cyclosporine, digoxin, amphotericin, hormonal treatment, renal disease, heart failure or sleep related movement or respiratory disease, psychiatric disorder, substance abuse, major life stressor, trans meridian flight in last 6 weeks)

500 mg elemental Mg daily

Administered as 414 mg MgO PO BID

(8 weeks)

Placebo

- ISI *

- Sleep log *

- Physical activity log

- Food diary

- Blood samples (Mg, cortisol, renin, melatonin)

Held et al. 2002

[25]

Germany

RCT (Cross-over)

12 healthy volunteers

(69)

(Sleep EEG)

Healthy older adults aged 60–80 years

(Psychiatric disorders, cognitive impairment, recent stressful event, substance abuse, trans meridian flight in last 3 months, shift work, medical illness, aberrations in blood chemistry/EEG/ECG, sleep related respiratory or movement disorder)

729 mg elemental Mg daily

Administered as an up-titration of 403 mg MgO PO daily × 3 days, 403 mg MgO BID × 3 days, and 403 mg MgO PO TID × 14 days

(Treatment intervals of 20 days duration separated by 2 weeks washout)

Placebo

- Sleep EEG *

- Blood samples (ACTH, cortisol, renin, AVP, ATII, aldosterone) ^c

Yes (voluntary report)

Nielsen et al. 2010

[26]

United States of America

RCT (parallel)

100 older adults

(59)

(PSQI)

Adults > 51 years with global PSQI score > 5 indicating poor sleep quality

(BMI > 40, respiratory tract disease, COPD, use of O2 or CPAP, use of ACEi, Mg-retaining or potassium sparing drugs)

320 mg elemental Mg daily

Administered as

320 mg Mg citrate PO two tablets each morning and evening and one tablet at noon

(8 weeks)

Placebo

- PSQI *

- Food diary

- Blood samples (Mg, erythrocyte Mg, calcium)

- Urine samples (Mg, calcium, citrate)

a – Acronyms: Mg Magnesium; PO Per os / to be taken by mouth; BID Bis in die / twice a day; TID Ter in die / three times a day

b - All outcomes reported in each study are listed. Relevant outcomes to review question are starred (*)

c – Other acronyms: ACEi Angiotension Converting Enzyme inhibitors, ACTH Adrenocorticotropic hormone; AVP Arginine vasopressin; ATII Angiotension II, BMI Body mass index in kg/m², COPD Chronic obstructive pulmonary disease, CPAP Continuous positive airway pressure, ECG Electrocardiogram, EEG Electroencephalogram, RDA Recommended daily amount