Additional supplements of glycine (an amino acid), can increase central nervous system (CNS) concentrations. Theanine is thought to work for stress-induced anxiety. It is also used for its relaxing and anti-anxiety effects. Magnesium helps relax muscles and is believed to block the release of excess excitatory neurotransmitters in the brain. Magnesium is also used orally for treating attention deficit-hyperactivity disorder (ADHD), anxiety and chronic fatigue syndrome (CFS).