Suggestions not to behave bad in League while in period?

1. Mute
2. Don't respond to trolls
3. Mute
4. Don't say it, think it
5. Mute
6. Don't blame your team for your mistakes
7. Mute
8. Don't call people "noobs", instead give them advice
9. Mute
10. Don't go AFK
11. Seriously, did I mention they have a mute option?

Period mood swings are a myth.....

Don't play league while on your period.

Uh caffeine helps me when I'm experiencing menstrual bitchiness and brain fog. It really does impact my ability to play the game. If you drink one energy drink normally, drink two. My symptoms have also been reduced by birth control. This is what you're talking about, right?

Find friends who don't mind and turn off All Chat.

Have upbeat or relaxing music in the background and avoid angry-at-the-world stuff. Depends on what you need.

Take longer breaks between games to cool off.

Get some excercise before playing.

Nothing working and you still need to vent? Punch a pillow or similar item. Seriously, there used to be a pro player (might still be playing, I can't remember off-hand which one) who would do that.