unexpected periods

I have read information debunking this phenomenon but observation has shown it often enough to believe that “stress, heat, and excitement” can trigger a woman's period, as can rooming with a woman who is having her period. Although statistically improbable, on one trip the females of the group I was with, about a dozen, managed 100%. So, the related hints are:

• “Surprise” periods are common at camps, retreats and trips. Always have extra supplies and an adult woman available.
  
• Adult men should not be clueless. If a girl becomes distracted and uncomfortable, needing to go to the bathroom, or perhaps even unwilling to stand up, don't press the issue. You may have to help draw attention away from her and let her slip out to clean up.
  
• Younger girls are much more likely to be caught by surprise than older girls, but even high school girls can be caught off guard.