In some ways, SUDEP is akin to SIDS (sudden infant death syndrome/crib death). The patient, in the majority of cases, dies unattended in their sleep and is found dead lying on his/her stomach. This may often be misleading for medical examiners. Often, diagnosis may be based on what telltale signs of other types of death are not there because of the mysterious nature of SUDEP.
In fact, there have not been many witnessed incidences of SUDEP. A seizure may influence the occurrence of SUDEP, however SUDEP does not always appear to be preceded by a visible seizure event. In many cases, the patient was very healthy and had no other health-related problems before going to bed.