Here is a fascinating study that would seem to validate some of the tenets of socionomic theory:
Happiness and Sadness Spread Just Like Disease
by Brandon Keim, Wired Science
There may be a literal truth underlying the common-sense intuition that happiness and sadness are contagious.
A new study on the spread of emotions through social networks shows that these feelings circulate in patterns analogous to what’s seen from epidemiological models of disease.
Earlier studies raised the possibility, but had not mapped social networks against actual disease models.
“This is the first time this contagion has been measured in the way we think about traditional infectious disease,” said biophysicist Alison Hill of Harvard University...
It will be interesting to see follow-ups to this type of work. At the very least, it gives you a tool to help understand how your individual mood swings work in context of the larger social organism.