Two ingredients, two routes to relaxation
Magnesium glycinate is magnesium bound to two molecules of the amino acid glycine, and both halves are biologically active. Magnesium acts as a natural blocker of the excitatory NMDA glutamate receptor and supports normal GABA-A receptor function, which together favor reduced neuronal excitability. The glycine carrier is itself an inhibitory neurotransmitter in the brainstem and has been independently associated with faster sleep onset in small studies.
The chelate form is also valued for being well absorbed and unlikely to cause the loose stools common with magnesium oxide, which makes it a practical bedtime choice.
How strong is the sleep claim
Evidence that magnesium supplementation improves sleep is strongest in people who are deficient or older, where correcting low magnesium status may help. In well-nourished individuals the benefit is less clear, and most trials are small. The mechanism is plausible but the size of any sleep effect should be considered modest and individual.
This is educational information, not medical advice. People with reduced kidney function should be cautious with magnesium and consult a qualified professional before supplementing.