Okay STells, here's a serious answer for you.
I have known several people who had to wear mouthguards due to a condition called bruxism. Mostly it's caused by stress, anxiety and often affects A-type crazy personalities. People who don't know they have it often wonder why they have jaw pain or terrible headaches. It's no wonder why. The sound of someone grinding their teeth during sleep can be so loud it wakes the person next to you. Very strange sound too. I could be wrong, but seems like something that affects more men than women. Maybe that's just my little sampling.