Circadian rhythms of arousal in parent–child interaction: a 24-hour co-regulation process

Abstract Caregivers play a critical role in regulating infants’ arousal and synchronizing biological rhythms with environmental cycles. In this article, we examine how caregiving behaviors shape the development of circadian rhythms in early childhood, focusing on the integration of sleep–wake cycles and the function of the hypothalamic–pituitary–adrenal axis. We propose a framework that is grounded in dynamic systems theory and transactional models, and that highlights the bidirectional interactions between caregivers and infants in establishing a cohesive 24-hour regulatory system. We also explore the cascading effects of disruptions in sleep and stress regulation, emphasizing how responsive caregiving supports adaptive outcomes while inconsistent caregiving may lead to dysregulation.