I was thinking about school shootings today. Has anyone else noticed how there seem to be a disproportionate number of mass shootings in March/April?
My mother is bipolar, and during the 15 years she was on Lithium, she most often had psychotic/manic episodes in September. When we realized there was a definite pattern, we discovered seasonal affective disorder. The changing of the seasons from winter to spring can trigger mania (and accompanying psychosis) in people prone to it.
Of course, spring comes in March and April in the Northern Hemisphere. Here's a list of school shootings. I looked at the last ten years of data, from 1998 to 2007. I removed one incident which was not in the Northern Hemisphere (Argentina). I removed an couple of incidents which were accidental. The list also includes foiled plots that didn't materialize into actual shootings.
63 incidents. 27 were in March and April. Maybe there's not enough data, but that seems to be 42% of the incidents in only 16.6% of the time.
Incidentally, the Argentinian incident was in September.