Sudden unexpected nocturnal death syndrome in the Mariana Islands. Sudden unexpected nocturnal death syndrome (SUNDS) is a distinct clinical entity in previously healthy, young, Southeast Asian males. It is well known in the Philippines and more recently recognized in the U.S. by nonspecific autopsy findings, with no evidence of underlying disease and absence of toxic drug or alcohol levels. In 1973-89, 14 cases of apparent SUNDS came to coroner's autopsy in the Commonwealth of the Northern Marianas (CNMI) and Guam. All 14 cases, with the exception of one Yapese, were previously healthy, male Filipinos, aged 23 to 55, who were either found dead in bed, or described by their colleagues as having nocturnal seizure activity consisting of gurgling, frothing, and tongue biting immediately prior to death. Autopsy findings showed no anatomic findings to account for death. Comprehensive serum and urine drug analyses were negative. All decedents showed absence of significant atherosclerosis or grossly detectable structural cardiac anomaly, while four showed cardiomegaly. Migrants from Southeast Asia carry with them a pre-disposition to this syndrome, which appears to decline with longer residence in the new country. The mechanism of death in SUNDS is believed to be ventricular fibrillation, possibly precipitated by sudden sympathetic discharge. Studies suggest at least some deaths may be associated with an abnormal cardiac conduction system. Acute pancreatitis has been a finding in some series, but not our cases. Why the condition is virtually limited to males and seemingly sleep-triggered, has not been adequately explained. Stress and depression are believed to be predisposing factors. 