Social media is the main form of communication and self-expression among Millennials (young adults born 1981 through 1996). Its use is gaining more breadth worldwide, while its effect on mental well-being remains much disputed. At the same time, current research points out to unprecedented levels of anxiety among this generational cohort. The present article aims to understand the patterns and the neurophysiological fundamentals of social behavior and human connectedness, as well as its evolutionary basis, in relation to increased engagement in electronic communication by Millennials. An in-depth analysis of social emotions and their regulatory role, as well as the mechanisms of social homeostasis are presented.  This theoretical framework was used to study the relationship between social behavior, alienation, anxiety and social networking sites.