L'actigraphie comme mesure de sommeil à l’âge préscolaire : liens avec la sécurité d’attachement et les comportements extériorisés

The overall objective of the thesis was to contribute to the expansion of the current state of knowledge on young children’s sleep. The thesis consists of four empirical articles. The first article compared the validity of three algorithms for detecting sleep with actigraphy by comparing them to polysomnography in preschoolers. The putative influence of device location (wrist or ankle) was also examined. 12 children aged 2 to 5 years simultaneously wore an actigraph on an ankle and a wrist during a night of polysomnography recording at home. The results showed that actigraphy generally provides good detection of sleep, but weaker detection of wakefulness. The article also suggests that young children require an algorithm adapted to their level of nocturnal motor activity. Finally, sleep variables derived from the ankle and wrist were not statistically different, suggesting that the validity of the actigraphy is not influenced by the location of the monitor. The second article examined associations between actigraphy, maternal sleep diaries, and the parent-completed Child Behavior Checklist (CBCL) sleep items, which are instruments widely used by clinicians and researchers to assess sleep among young children. 80 middle-class families participated in this study when children were aged 2 years. Children wore an actigraph monitor for a 72-hour period and mothers completed a sleep diary during the same period. Both parents also completed the CBCL. The results show that these sleep measures assess different aspects of children’s sleep, and suggest a particularly low concordance between the subjective and objective sleep measures. The third article used objective measures of sleep and attachment to assess the longitudinal links between mother-child attachment security and subsequent sleep, while partialling out child dependency. 62 middle-class families were met twice. Security and dependency of attachment were assessed with the observer version of the Attachment Q-Sort when the child was 15 months. At the age of 2 years, children wore an actigraph monitor for a 72-hour period. Results indicated that children more securely attached to their mothers had higher nighttime sleep duration and efficiency, and these predictions were not confounded by child dependency. The aim of the fourth article was to investigate the concurrent and longitudinal relations between sleep and externalizing symptoms among young children. Sixty-four families were met twice. At the age of 2 years, children wore an actigraph monitor for a 72- hour period and both mothers and fathers completed the CBCL. When children were aged 4 years, both parents as well as the daycare educator filled the CBCL. The results show that child sleep is associated with concurrent externalizing symptoms and with an increase in externalizing symptoms over time. Associations between sleep efficiency and externalizing symptoms were moderated by child sex, such that links were only significant among boys. Finally, the results of the four articles are integrated into the general discussion.

Keyphrases: CBCL, Children's sleep, Sleep duration, Sleep quality, Actigraphy, Sleep diary, Polysomnography, Attachment, Externalizing symptoms