If death is as painful as thousands of scorpion bites, then how do some people die peacefully in sleep?

From: Suren

I heard in few lectures that the ulitmate problems of life are birth, old age , disease and death . It is said in scripture (Garuda Puraan) , that when a man dies he suffers an unbearable pain of 42,000 scorpion bites .
But we have seen many times that people die peacefully and there are no signs of such a trauma . For eg – few people pass away while asleep etc ..
I would be grateful to you if you could shower some clarification on this .