Magnesium glycinate is a highly bioavailable chelate that targets neuro-muscular relaxation and stress physiology. This paper synthesizes evidence on its roles in alleviating depression, anxiety, and insomnia, and in supporting cognitive performance in high-stress individuals. We review mechanistic pathways (GABAergic tone, HPA axis balance, circadian and sleep architecture), summarize human data on mood and sleep outcomes, and provide practical guidance on dosing, safety, and interactions. The formulation’s tolerability and synergy with other nutrients (e.g., L-theanine, B-vitamins) are highlighted to inform integrative approaches for mental well-being and cognitive resilience.