Venrak
Bluelight Crew
One example (there are many) is how women's menstrual cycles align, when they live in the same house.
This has more to do with psychic bonding, and crudley put, is a manifestation of two or more individuals having the same circadean rythm. This syncronicity kinda spreads across the entire system. We are like little neurons osscilating back and forth.

This relationship between individuals is a core part of shamanism/sorcery; manipulating this bond through ritual acts that effect the tribe as a whole, for good or evil respectively.