Fetal Sleep: A Cross-Species Review of Physiology, Measurement, and Classification
Journal:
arXiv
Published Date:
Jun 27, 2025
Abstract
Fetal sleep is a relatively underexplored yet vital aspect of prenatal
neurodevelopment. Understanding fetal sleep patterns could provide insights
into early brain maturation and help clinicians detect signs of neurological
compromise that arise due to fetal hypoxia or fetal growth restriction. This
review synthesizes over eight decades of research on the physiological
characteristics, ontogeny, and regulation of fetal sleep. We compare
sleep-state patterns in humans and large animal models, highlighting
species-specific differences and the presence of sleep-state analogs. We review
both invasive techniques in animals and non-invasive modalities in humans.
Computational methods for sleep-state classification are also examined,
including rule-based approaches (with and without clustering-based
preprocessing) and state-of-the-art deep learning techniques. Finally, we
discuss how intrauterine conditions such as hypoxia and fetal growth
restriction can disrupt fetal sleep. This review provides a comprehensive
foundation for the development of objective, multimodal, and non-invasive fetal
sleep monitoring technologies to support early diagnosis and intervention in
prenatal care.
