Soutenance de thèse Lucie Malevergne "Impact de la sieste et du sommeil de nuit sur les performances cognitives de l'enfant scolarisé en maternelle"

Jury :
- Géraldine RAUCHS (rapportrice) – Inserm, UNICAEN
- Alex DE CARVALHO (rapporteur) – Université Paris Cité
- Jonathan FERNANDEZ (examinateur) – Université Paris-Est Créteil
- Alice GOMEZ (examinatrice) – Université Claude Bernard Lyon 1
- Stéphanie MAZZA (directrice de thèse) – Université Claude Bernard Lyon 1
- Amandine REY (co-directrice de thèse) – Université Claude Bernard Lyon 1

Lien visio : https://univ-lyon1.webex.com/univ-lyon1/j.php?MTID=md7ed2179dcc3ea2cc02857388ebd089e

Abstract

During the preschool years, children undergo a major sleep transition, gradually shifting from a biphasic pattern with an early afternoon nap to consolidated nighttime sleep. This evolution relies on brain maturation, which allows children to accumulate sleep homeostatic pressure more slowly and consolidate learning more efficiently, reducing the need for napping. In France, this transition occurs within a specific educational context, characterized by compulsory schooling from age 3 and collective nap organization in preschool. Currently, 87% of French children attend public preschool where napping is systematically offered in the first level of school (ages 3-4), varies across schools in the second level of school (ages 4-5), and it is no longer offered in the third level of school (ages 5-6). This age-based organization contrasts with the high interindividual variability in sleep needs documented in the literature.

This thesis examines the nap transition through three complementary objectives: (1) to document napping practices in French preschools and their alignment with individual needs, (2) to examine the relationship between daytime and nighttime sleep under ecological conditions, (3) to evaluate the relationships between napping and cognitive development.

Three complementary studies were conducted with preschool-aged children. A nationwide survey of 1,498 parents of preschool children identified five distinct napping profiles based on their frequency, duration, and acceptance at school and home: regular nappers (napping daily in both contexts), frequent nappers (frequent but not systematic napping), school-only nappers (only at school), home-only nappers (only on weekends), and non-nappers. An objective sleep measurement study using actigraphy over seven consecutive days, conducted with 85 children aged 3 to 5 years, examined the interaction between napping and nighttime sleep under ecological conditions. Finally, a longitudinal study of 100 children over two years combined sleep measurements and cognitive assessments.

The results reveal high interindividual variability in napping habits. The proportion of children napping decreases with school level (from 98% to 40%). This transition is accompanied by a reduction in total sleep time that increased nighttime sleep does not fully compensate for. The analysis of nap habit profiles reveals a marked discrepancy between collective practices and individual needs. Notably, school-only nappers and home-only nappers represented one-third of children, revealing that many children only nap in a single context. The examination of nighttime compensation reveals that each hour of napping is associated with only a 14-minute decrease in nighttime sleep duration. Sleep-cognition relationships vary across cognitive domains. Language development is associated with shorter naps and longer nighttime sleep, reflecting underlying maturation processes. For attention, nap effects are complex and vary according to individual habits and the type of attentional process assessed. Memory consolidation is affected neither by napping nor by nap habits. Nevertheless, children who have transitioned out of napping show more efficient nighttime consolidation, consistent with the hippocampal maturation model.

Taken together, these results demonstrate that age is insufficient to determine napping needs. The coexistence of five distinct profiles within the same age group, along with the fact that one-third of children only nap in a single context (school or home), reveal that age-based collective organization does not correspond to the diversity of individual physiological needs. It therefore appears essential to adapt nap management to individual needs rather than age. A flexible approach, allowing for the identification of children who still benefit from napping while offering restful alternatives for those who have transitioned, appears to be more consistent with current scientific evidence.

Keywords: Sleep, Nap, Cognitive development, Actigraphy, Brain maturation, Preschool children