Researching sudden unexpected infant death

Current theories about the causes of SIDS include disturbances to the baby's sleep organization and temperature control – factors under the control of the biological clock. Premature babies have a delayed development of biological rhythms, which usually develop at nine to 12 weeks of age. It is intriguing that the peak incidence of SIDS coincides with the expected time of maturation of babies' rhythms.

Sudden infant death syndrome (SIDS) is the major cause of death in young infants in the western world. Factors that increase the risk of SIDS are known (e.g. overheating and cigarette smoke) but the actual cause of death is unknown.

A malfunctioning biological clock (circadian rhythms which recur on a roughly 24-hour basis) may be a factor in SIDS, because of the clock's key role in regulating sleep, temperature and hormonal rhythms. The development of mature stable sleep rhythms is an important part of infant development. The neurological processes involved in the control of the sleep-wake cycle develop and mature between 2 and 6 months of age. The Adelaide Baby Study seeks to generate baseline data about the normal development of infants' sleep-wake cycle within the home environment and under contemporary child-caring circumstances. The study is unique in that it looks at normal sleep development in the home rather than in a laboratory environment. Australian research (Adelaide University) also suggests that fluctuating body temperature may be important in SIDS. Young infants have greater difficulty controlling their body temperature than older babies and children. With varying internal temperatures, the fluidity and function of the surfactant lining the lungs may be altered in a way that causes respiratory distress.

However, all kinds of rhythms are important for the well-being of the baby. There is a possibility that the rhythms in children who are at risk of SIDS develop out of synchrony with each other. Drugs taken by the mother during pregnancy may contribute to the lack of synchrony. Three drugs are being studied by scientists in Adelaide: nicotine and caffeine because they are used by many pregnant and breast-feeding women and both have been implicated in adverse changes in the developing foetus; and cocaine because it is a major problem in pregnancy in the USA.