We've all read about the public hysterias which lead up to wars and other unpleasant things. Public mood causes people to change their personal behavior. The summation of personal behavior is the public mood. Economic activity is an aspect of the public mood. The other link you make, between personal biochemistry and the longwave is not obvious.
Biochemistry changes on an hourly basis, and the longwave occupies many years.
Surely, with less serene surroundings, a higher percentage of people will display mood disorders. The guy who wrote it may be a mad bomber, but he has some significant insights into modern society. In my opinion. Anyway, if you rachet up the level of stress in a society, more of the most vulnerable psyches drop out. That is, if you are a low status male, and are not in control of your life, you may as well kill or be killed in an attempt to gain social status.