Magnesium Glycinate Improved Sleep in 155-People Study

Stanfield contrasts the intention-to-treat (ITT) analysis that included all randomized participants (some of whom didn’t take the supplement as directed) with the per-protocol (PP) analysis that only considered compliant participants. The PP analysis revealed a 1.9-point advantage over placebo and a total ISI reduction of 5 points—almost hitting the 6-point threshold for clinical significance. He explicitly concludes that ‘the more a person sticks to the protocol and takes the magnesium supplements, the more potential for their sleep improvements they will see.’ This is a practical behavioral insight: if you’re going to use magnesium for sleep, don’t skip doses; consistency yields the larger effect seen in the compliant subgroup. This underscores the importance of adherence in supplement trials and real-life use, and explains why the initial 1.6-point figure understates magnesium’s potential.

Stanfield explains that the body’s 25 g of magnesium resides mostly in bone (50-60%) and soft tissues, with less than 1% in blood. The kidneys tightly control blood levels, so a deficiency in tissues can exist with normal serum measurements. He tells patients to focus on adequate dietary intake instead of lab tests, as they are misleading. This advice is backed by the epidemic of deficiency (45% of US population) that would be missed by routine blood work. He does reserve testing for acute scenarios or malabsorption syndromes, but for general wellness, aiming for the RDA through food and a low-dose supplement is a more reliable strategy.

Stanfield explains that because the vast majority of magnesium resides inside cells or in bone, and blood levels are homeostatically controlled, serum magnesium measurements have little correlation with total body stores. Consequently, a person can have a ‘normal’ blood test yet be functionally deficient. This renders routine blood testing unhelpful for assessing magnesium status in most people, except in acute scenarios or with malabsorptive conditions like Crohn’s disease. Instead, he advises his patients to focus on ensuring adequate dietary intake (and supplement if needed) rather than chasing lab numbers. This advice is reinforced by the fact that 45% of the US population may be magnesium deficient, yet many would test normal on standard panels. Thus, the protocol is to target the RDA through food and, if necessary, a low-dose supplement, rather than rely on a misleading biomarker.