What does having blood on spit(saliva) could indicate?

Question

For two days now I clearly notice blood on my spit during the midnight around 1-2am. I don't have any respiratory conditions nor dental problems that I know of (I'm not feeling any toothache or gum pains as of the moment) . The blood goes away after continuous spitting. 

So I'm quite curious of what could have caused this and what could it mean. Do you know certain conditions that have this specific symptom? Also, if you know any reliable site on the inernet that could provide comprehensive info about having blood on spit(saliva), pls include so. Thank you.

Answer 1

I occasionally have a light colored blood in my spit every once in awhile and it goes away soon. This usually happens when I have a cold. So that could be it.

If it continues too much I'd go to a doctor and have it checked out. But most likely it's just a temp thing and non harmful.

Answer 2

Conditions of the mouth such as gum disease and tooth extraction may cause spitting blood. Spitting blood that comes up with a cough is commonly associated with lung cancer, bronchitis, and pneumonia. 

These may cause spitting up of bright red blood, rust-colored mucus, or mucus that contain streaks of blood.