In various Asian populations there are reports of sudden and unexpected deaths, often at night, in apparently healthy young adults.
In Japan there is pokkuri disease.
Among the Hmong people there were sudden unexpected nocturnal deaths, which may be ascribed to supernatural encounters.
If an autopsy is performed, then usually no organic heart disease or other explanation for the death is found. Toxicologic tests are negative.
The most likely explanation is a fatal cardiac arrhythmia such as ventricular flutter. Without cardiac monitoring any arrhythmia may go undetected.
