I ve worn a nightguard for a few years due to nighttime grinding of my teeth . I got a new nightguard from my dentist a few months ago, and it feels comfortable. Oddly, I ve woken up a few times in the past few weeks to find a good amount of blood on half of the inside of my nightguard. I cannot figure out where the blood is coming from - I have no visible bleeding , pain, discomfort, or swelling in my mouth. Where could the blood be coming from, and should I be concerned?