Is there a study out there that links vitamin B12 specifically with lowered or raised melatonin? And related to that, is there any relation to high amounts of B12, and lack of sleep or other sleep issues? I take B12, as a vegetarian, as I am reported to be deficient, but when I take a full recommended dose (as opposed to half) it seems to be interfering with my sleep. As I am melatonin sensitive, I am exploring a link.
I had been sleeping fine all along with a mild vitamin deficiency, dropping off to sleep within a minute or so after hitting the pillow. The nights after the days where I took a full dose of B12, I was up for hours past my bedtime in hyper alert mode. No caffeine was taken those days.