Why some people act strangely during full moon?

There is no proven correlation between moon phases and human behaviour that would fall into the "lunacy" category. An article from Psychological Bulletin [Vol 97(2), March 1985) called "Much ado about the full moon: A meta-analysis of lunar-lunacy research" written by J Rotten and I W Kelly published the results of a meta-analysis of 37 studies examining the relationship between moon phases and human behaviour and found that moon phases account for no more than 1% of variances that would be termed as lunacy. "Lunacy of the moon", an article in the Psychological Bulletin [Vol 85(5), September 1978 written by David E Campbell and John L Beet came to a comparable conclusion.

However, there are some people who believe that the moon's gravitational pull can have effects on the human body, perhaps influencing our behaviour. The theory suggests that because the moon's gravitational pull affects our ocean tides, perhaps it can have some kind of pulling effect on the water in our body. There is no scientific proof of this theory that I'm aware of.