Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans

Hashimoto S1, Kohsaka M, Morita N, Fukuda N, Honma S, Honma K
Neurosci Lett. 1996 Dec 13;220(2):129-32

https://www.ncbi.nlm.nih.gov/pubmed/8981490