Ontogénèse des états de vigilance et de la rythmicité circadienne : de la période fœtale aux six premières années

It is likely that fetuses have functional circadian pacemakers entrained by maternal circadian rhythms. Circadian cycles are clearly present in human heart rate, movements and respiration in the last trimester of gestation. These circadian rhythms are lost at birth. In the neonate sleep and wakefulness follow an ultradian rhythm. Sleep/wake and biologic circadian rhythmicity reappears during the first weeks of life and is dependent on time cues. Emergence of circadian rythmicity probably plays a key role in the consolidation of nocturnal sleep.