In Rajasthan in India, locals know a snake called peevna in the local language. Many of my relatives live there in villages in open deserts. They see many kinds of snakes every day.
The word peevna is basically derived from the Hindi word peena, which is a verb meaning to drink. But in the case of this snake, the drinking being referred to is the process of inhaling the warm air from the nose or mouth of a sleeping man. Hence they call it peevna.
Locals describe this snake as follows:
It is afraid of light. It just sits on the waist of any sleeping human, and then it "drinks" the warm breaths. After the breath gives the snake some comfort, it releases the venom into the mouth of the human. Finally, it hits the man with it's tail and leaves. The man dies once the sun light falls on him if he is not treated.
A similar description of this snake is mentioned on many Hindi blogs. However, I can't trust these stories.
Given all that, what snake is it and is it and is it even possible that this snake behaves like this?
A recent case has been mentioned here. And it is real. The villagers have reported the case. But it's in Hindi. Kindly translate that page, as it would be helpful to answer.
Now a doctor also said that it is a Karait kind of snake.
When I searched it on Google, I found this.
In common names, Peewana is also mentioned. So I guess this is the snake. But doubt is, the photo on the blog I shared is different than this. No only this, my relatives also define the look and feel of the snake like the one on blogs. So doubt remains.