Many years ago my grandmother, who lived in Nové Zámky, Slovakia peacefully died in her favorite armchair. Seems that she was doing a bit of afternoon reading, nodded off and never woke up. She had never had a major illness, nor had she ever spent any time in a hospital. That was more than forty years ago and it has taken me all these years to discover that she died of/with 'pokkuri'. 'Pokkuri' [ ぽっくり ] is a unique Japanese word/concept of dying peacefully in your sleep, just quietly passing into oblivion . No muss, no fuss, just 'popping off'. . I guess even a heart attack might count as 'pokkuri', if of course it were quick enough.
In Japan there are several temples to this kami, or god, of 'pokkuri'. The large Kichidenji Temple is outside Nara, and has a steady stream of visitors requesting a final gift of 'pokkuri'. I wonder why the English speaking world doesn't have a nice word/concept like 'pokkuri'?