Background: Sudden and unexplained death in sleep (SUDS) is a leading cause of death of young men in several Asian populations, but the history and epidemiology of SUDS are not well known.
Methods: Autopsy records were reviewed in Manila in a study of the classification of SUDS. Death certificates filed in Manila during 1948-1982 were then reviewed in a study of SUDS incidence. A nested case-control study of death certificates examined birthplace as an indicator of SUDS risk.
Results: The classification of SUDS cases in Manila during 1948-1982 (N = 722) evolved from the folk term, bangungut ('to rise and moan during sleep'), to various descriptions of post-mortem artefacts. The characteristics of victims in each of the groups were similar: 96% male, mean age 33 years, and modal time of death 3:00 a.m. The deaths were seasonal, peaking in December-January. SUDS victims were more likely than deceased controls to have been born outside of the Manila region (relative odds = 2.11; 95% CI: 1.59-2.78). The SUDS rate for men aged 25-44 years increased from 10.8 to 26.3 per 100000 person-years from 1948 to 1982.
Conclusion: The death certificate classification of SUDS in Manila has changed considerably, obscuring an increase in incidence. SUDS appears to be a regional phenomenon in Southeast Asia and environmental causes are likely because the deaths are seasonal, increased over the timespan studied, and are more common among migrants to Manila than among those born there.