human biology - What biological systems are affected by Vitamin B6 (or B vitamins in general)?

B vitamins and particularly the B6 vitamin appears to the one of the main ingredients in energy drinks.

There has been anecdotal evidence from people interested in dreaming that ingestion of vitamin B6 at night time changes the pattern of dreaming and is likely to produce "lucid" dreams.

From a biological standpoint, what is the effect of the B6 vitamin on the human body and brain? Do other animals require the same vitamin?

Are B vitamins in any way related to the circadian rhythm regulation within some organ systems? Does it speed up metabolism?

I would be grateful for any scholarly papers on the subject or keywords that I may look up myself.

Thank you!