0048 CEREBRAL SEROTONIN EXPRESSION PREDICTS DAYTIME SLEEP AND SLEEP DEVELOPMENT IN INFANT RHESUS MONKEYS

Abstract Introduction: Cerebral serotonin expression and sleep share a complex and as yet unclear association in early development. Though serotonin is linked with sleep-wake patterns in early childhood, whether this association emerges during infancy remains to be discovered. We hypothesized that the developing serotonergic system will be associated with the development of sleep-wake patterns. Methods: We investigated the associations between cerebral serotonin expression and sleep development during the first month of life in 152 nursery-reared infant rhesus macaques (Macaca mulatta). Cerebral serotonin expression was determined using cerebrospinal fluid serotonin metabolite 5-hydroxyindoleacetic acid (CSF 5-HIAA) concentrations, relative to weight, sampled at 2 and 4 weeks post-birth. Sleep-wake states were rated by trained observers every two hours from 0800-2000 hours. Sleep-wake states were scored as awake=1, drowsy=2, or asleep=3. For analyses, daytime sleep-wake states were averaged across the 7 days prior to each CSF sampling. Paired-samples t-test, Wilcoxon signed ranks test, and Spearman’s ρ were utilized to explore associations between time points, averages, and change scores (week 4 minus week 2) for both CSF 5-HIAA and sleep-wake states. Results: Daytime sleep (t(239)=17.27, p