For some time now, I've been idly working through a theory about how the rising diagnosis of depression (just about everyone I know is on some sort of antidepressant) is linked to the fact that we, as a people, don't have to spend our days, sunup to sundown, actively trying to survive. Because life is now, for most - at least in first-world countries - a lot easier, we have a lot more time to develop neuroses.

Hence, more depression.

Looks like that idea isn't as brilliant and original as I thought it was:

How we learned to stop having fun

"...could this apparent decline in the ability to experience pleasure be in any way connected with the decline in opportunities for pleasure, such as carnival and other traditional festivities?"