Is sudden unexplained nocturnal death a breathing disorder?

Sudden unexplained nocturnal death syndrome (SUNDS), or 'Lai Tai' in northeastern Thai dialects usually occurs during sleep in healthy young adults, mostly male. The characteristics of Lai Tai are similar to SUNDS which has been reported in several southeast Asian countries and in Japan by the name of 'Bangungut' in Tagalog or 'Pokkuri' in Japanese. The condition has been recognized by the people in the northeastern part of Thailand for many years. Elderly people in the region have described 'Lai Tai' victims as making loud groans and showing signs of difficulty in breathing or labored respiration, who become rigid and die. Data, from relatives or those who had witnessed the episodes of deaths, revealed that the deaths usually occurred in the same manner as described by the elderly. The data also reported that the patients were unresponsive and difficult to arouse. From these reports it is likely that the instability of the physiological systems, especially respiration, in particular during the REM phase, may play some roles in precipitating the sudden death.