[Sudden death syndrome in the newborn infant and sleep]

It seem increasingly obvious that sudden death is a multifactorial syndrome, the result of respiratory and/or cardiac dysfunction in responses to various causes. Cardiorespiratory and neurophysiological explorations performed during sleep have considerably increased our understanding of the syndrome. They have been at the root of all recent theories, and they make it possible to rule out a likely cause in infants "rescued" from sudden death. Some of these explorations may be used for screening purposes, as they sometimes evaluate the risk of apnea or cardiac accident capable of causing sudden death. The development of sleep during the first 6 months of life plays de determinant role in the syndrome. Slightly more than 80 p. 100 of deaths occur during a period of presumed sleep. The 1 to 6 months period is characterized by very rapid changes in the quality and organization of sleep: there is a substantial increase in quite sleep time, during which the child is most probably vulnerable, and a decrease in agitated sleep time which at that age is thought to protect against sudden death. This is also the period of life where sleep stability increases and where al circadian rhythms are constituted and harmonized with each other. The rapidity and nature of these changes probably makes this period a time of risk. Another factor of importance is the problem of sudden infant death is the ability to wake up. Recent studies have shown that infants believed to be at risk of sudden death seem to have disturbed awakening mechanisms.