Behavioral-state development and sleep-state differentiation during early ontogenesis.

Sleep is a key process in neurodevelopment and essential for the maturation of fundamental brain functions. Premature birth can disturb the initial steps of sleep maturation, which may contribute to the impairment of neurodevelopment. It is thus fundamental to understand the maturation of the various sleep states and the quality of cerebral function in each vigilance state, as well as the development of sleep cyclicity, in at-risk neonatal infants, particularly those born premature. The objective of this review is to provide a precise description of sleep states and cycles and their rhythmic organization in premature and term newborns according to their gestational age. Technical aspects of polysomnography, which requires a high level of expertise in neonates, are also described. Principles of the visual interpretation of polysomnography, including the simultaneous analysis of behavioral (spontaneous motricity and eye movements), polysomnographic parameters (electro-oculogram, electrocardiogram, respiration), and electroencephalography patterns are presented. The neurophysiology of sleep ontogenesis and its interaction with brain maturation are discussed, highlighting the crucial role of sleep states and their duration in premature newborns. In particular, the involvement of myoclonic twitches in functional connectivity in sensorimotor development is discussed. Indeed, sleep quality, determined by combined polysomnographic parameters, reflects either normal or pathological developmental processes during the neonatal period. The fundamental place of neurophysiological explorations in the early detection of sleep disorders is discussed, as well as their potential consequences on neurodevelopmental care to improve the prevention of neurodevelopmental impairment.

A video polysomnographic study of spontaneous smiling during sleep in newborns.

The objective of the present study was to confirm the link between spontaneous smiling and active sleep in newborns, and to identify the role of the cortex in the generation of spontaneous smiles. A total of 12 healthy newborns born at term and three infants with major congenital abnormalities (two with hydranencephaly and one with a left hemispherectomy) were evaluated by video and polysomnography during a 3-hr sleep period. Smiles were graded and their association with isolated rapid eye movements and grouped rapid eye movements was analysed. In all, 383 smiles were recorded of which 377 occurred during active sleep. Smiles were shown to be significantly associated with active sleep (p < .0001) and with grouped rapid eye movements (p < .0001). Bilateral smiles were more frequent than asymmetrical smiles. Among asymmetrical smiles, left-sided smiles were more frequent than right-sided smiles (p < .0001). Maternal stimulation during active sleep did not increase smiles. Smiling was absent during active sleep only in the infant with total hydranencephaly in whom nearly all cortical tissue was absent. In conclusion, smiling occurs in healthy newborns, almost exclusively in active sleep and is associated with grouped rapid eye movements. In infants with major congenital abnormalities, smiling is abolished only when nearly all of the cerebral cortex is absent. These results support the hypothesis of the role of active sleep in the stimulation of neuronal circuits responsible for spontaneous smiling and emphasise the importance of cortical areas in newborn smiling.

The French Sleep Disturbance Scale for Children.

OBJECTIVE: The psychometric properties of the Sleep Disturbance Scale for Children (SDSC) have been shown to be accurate, even when translated into several languages. The aim of the present study was to translate, adapt, and validate the SDSC for a French-speaking population. METHODS: After forward- and back-translation, the tool was further translated and adapted into the French language. It was then pretested in terms of clarity on 33 French-speaking parents. Pretesting demonstrated that the questionnaire was well understood, indicating good clarity. During the validation phase, a total of 447 French-speaking parents of children aged between 4 and 16  years completed the SDSC. Among these, 66 children were diagnosed with sleep disorders by a pediatric specialist after a sleep consultation and polysomnographic recordings. RESULTS: The factor analysis revealed five factors: difficulty in initiating and maintaining sleep (DIMS), sleep breathing disorders (SBD), disorders of excessive somnolence (DOES), parasomnias (PARA) and non-restorative sleep (NRS). This psychometric structure is reliable and logical in comparison with the experts' diagnoses. Convergent validity, divergent and internal reliability are very good. Inter-parental concordance in scoring the child's sleep problem does show differences in the ways in which parents report their children's sleep patterns. Cut-off was calculated for the total score (45). CONCLUSION: This study validated a 25-item French version of the questionnaire. The French SDSC could therefore be used to aid screening of sleep disorders in the general population.