Magnesium is involved in over 300 enzymatic reactions in the human body - including muscle contraction, protein synthesis, nerve function, and energy production. Despite this, studies consistently show that a large proportion of the population fails to meet the recommended daily intake through diet alone.
Why Magnesium Deficiency Is So Common
Modern agricultural practices have depleted soil magnesium content significantly over the past 70 years. Processing grains removes the magnesium-rich bran and germ. Stress, alcohol, and high-intensity exercise all increase urinary magnesium excretion. The result: even people eating "healthy" diets are often falling short.
Forms of Magnesium: Why Glycinate Matters
Not all magnesium forms are equal. The most common - magnesium oxide - has poor bioavailability (~4%) and primarily acts as a laxative. Magnesium glycinate is magnesium bound to glycine, an amino acid with its own calming effects. It has high bioavailability (~80%), is well-tolerated without GI side effects, and glycine itself promotes sleep quality.
Other useful forms include magnesium malate (energy metabolism), magnesium threonate (blood-brain barrier penetration), and magnesium citrate (moderate bioavailability, common). For sleep and recovery specifically, glycinate is the first choice.
Magnesium and Sleep Quality
A double-blind, placebo-controlled trial published in the Journal of Research in Medical Sciences found that magnesium supplementation significantly improved sleep efficiency, sleep time, early morning awakening, and insomnia severity index scores in older adults. The mechanism involves magnesium's role in regulating GABA receptors - the primary inhibitory neurotransmitter system - and suppressing cortisol release at night.
Magnesium and Athletic Recovery
Magnesium is lost through sweat. Athletes training intensely can lose 10 - 15% of their total body magnesium through sweat and urine daily. Deficiency impairs muscle relaxation (causing cramps and soreness), reduces sleep quality (slowing recovery), and impairs glucose metabolism (reducing training fuel).
A 2010 study in the Journal of Sports Science & Medicine found that magnesium supplementation reduced markers of muscle damage and inflammation following exercise, and improved recovery compared to placebo.
Dosing
The recommended dietary allowance (RDA) for magnesium is 310 - 420mg/day depending on age and sex. For supplementation, 200 - 400mg of elemental magnesium glycinate taken 30 - 60 minutes before bed is the most common protocol. Starting lower (100 - 200mg) and increasing gradually minimises any initial GI adjustment.
Who Benefits Most
Athletes with high sweat rates, people under high stress, those with poor sleep quality, and anyone eating a diet low in leafy greens, nuts, and legumes are most likely to notice benefits. Even in well-nourished individuals, the calming effect of glycine makes this a useful sleep supplement.