Glycine calming

The smallest amino acid, and an inhibitory neurotransmitter in its own right. Its sleep evidence rests on polysomnography — objective sleep-onset latency shortened. Capped by T4: one Japanese group, no independent replication.

Micronutrient status increases it.

Dietary and endogenous synthesis from serine. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593

It increases Sleep.

Primary is now objective, not subjective: Yamadera 2007, Sleep Biol Rhythms 5(2):126-131 (doi 10.1111/j.1479-8425.2007.00262.x) used polysomnography -- glycine before bed shortened PSG latency to sleep onset (p=0.01) and to slow-wave sleep, and improved sleep efficacy (sleep time / in-bed time), without altering sleep architecture. Participants had habitual unsatisfactory sleep, mean PSQI 8.07. It also lessened daytime sleepiness on the Stanford Sleepiness Scale and improved memory-recognition performance. The mechanism is NMDA receptors in the suprachiasmatic nucleus driving peripheral vasodilation and core-temperature fall (Kawai 2015, Neuropsychopharmacology 40(6):1405-1416, PMID 25533534). The limits ARE real and stated: n=11 (8 women, 3 men, 30-57), single-blinded crossover, and — decisively — all of the human trials come from one Japanese research group with NO large independent replication published. Under T4 (>=2 independent groups) this evidence cannot reach the top tier however good the method is. A 2024 systematic review of glycine in human adults exists (Soh 2024, GeroScience 46(1):219-239, PMID 37851316). doi 10.1111/j.1479-8425.2007.00262.x · PMID 25533534

It reduces Daily energy.

Same independence problem: every human trial is from one research group, no large independent replication. The serotonin mechanism is rat and the 5-HT rise lasted about 10 minutes. PMID 21414089

It reduces Lowers wake signal.

Anatomical rather than inferred. IMMUNOELECTRON microscopy showed GlyT2-immunoreactive terminals making symmetrical synaptic contacts with the SOMATA and dendrites of orexin neurons, and double-labeling localized glycine receptor alpha subunits in the postsynaptic membrane. Not a pathway deduced from behavior — the synapse was photographed. The consequence: the Glycine → Sleep link and the Orexin → Sleep link are both drawn with opposite signs, and this edge shows they are not independent inputs. Part of what glycine does to sleep it does by silencing the wake peptide. The authors are careful: glycinergic inhibition of orexin neurons might play a role in physiological sleep regulation — the anatomy is established, the functional contribution inferred. PMC3174993

It increases Tissue remodeling.

Collagen is roughly one third glycine by residue, and estimates of endogenous synthesis fall short of what collagen turnover plus glutathione and creatine synthesis together demand. Carried by the intermediary-metabolism, micronutrient and redox reviews (PMC9967593; doi 10.3390/nu18132141; PMC12673670; doi 10.1016/j.molmet.2023.101755). Verbatim: “Thus, increasing glycine in the diet may well be a strategy for helping cartilage regeneration by enhancing collagen synthesis, which could contribute to the treatment and prevention of osteoarthritis”. doi 10.3390/nu18132141 · PMID 30006659 · PMC9967593

It increases Master antioxidant.

One of the three glutathione amino acids. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593

It increases Rapid energy buffer.

A creatine precursor with arginine and methionine. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593

It increases One-carbon metabolism.

The serine-glycine interconversion is a principal one-carbon source. Carried by the intermediary-metabolism, micronutrient and redox reviews. doi 10.3390/nu18132141 · PMC9967593

Hypnotic Sleep (Slow-Wave Architecture) →