A required cofactor in the conversion of tryptophan to serotonin and serotonin to melatonin - without sufficient B6, the whole downstream sleep pathway slows.

Vitamin B6, in its active form pyridoxal-5-phosphate, supports healthy sleep by acting as a key cofactor in producing serotonin and melatonin from tryptophan. Postmenopausal women often experience altered tryptophan metabolism due to oxidative stress and low-grade inflammation, which can lower melatonin output and disrupt sleep timing. Adequate B6 helps restore the body's own melatonin synthesis and stabilize circadian signaling.

Through its role in producing mood-regulating neurotransmitters, B6 also supports emotional balance and a sense of calm — indirectly easing the pre-sleep mental overactivity that interferes with falling asleep and improving overall sleep quality.

https://pubmed.ncbi.nlm.nih.gov/30562392/
https://pmc.ncbi.nlm.nih.gov/articles/PMC9292249/"

https://pubmed.ncbi.nlm.nih.gov/38769717/