If someone is in a coma from bleeding from cutting the veins in their arms with a knife how do they wake up bag how long does it take for it to happen?

Doctors give a variety of answers for how long comas last. The most popular answer is that it really depends on how the person is doing physically and emotionally. If their body is healing properly and if they want to even come out of it. You can try sitting next to their bed and talking to them, they can hear you even though they don't look like it.