APs and Fire Alarms

Seriously, what's with APs and fire alarms? Two years ago, the fire alarm went off in our building at 7:00 the morning of the AP lit exam. To continue this biyearly tradition, it went off last night at 3:40 in the morning. At least we didn't have school or an exam this morning, but still. Real fire alarms don't happen that often, but when they do they always seem to go off during AP season. Why?