Les ondes en sommeil lent au cours du vieillissement normal : marqueurs du processus homéostatique et de la cognition

Les ondes lentes (OL) et les fuseaux de sommeil (FS) caractérisent le sommeil lent. Ces ondes sont particulièrement vulnérables aux effets du vieillissement, et ce, dès le milieu de l’âge adulte. La signification fonctionnelle de ces changements demeure toutefois inconnue. Les OL constituent des marqueurs sensibles de la pression homéostatique au sommeil qui augmente avec la durée de l’éveil et qui diminue avec la durée de sommeil. L’hypothèse que les changements des OL puissent refléter une altération de la régulation homéostatique demeure toujours matière à débat dans la littérature. D’autre part, les FS et les OL ont tous deux été associés à la plasticité cérébrale et à la cognition. La correspondance entre les ondes en sommeil lent et le fonctionnement cognitif au cours du vieillissement normal demeure peu étudiée et les résultats sont inconsistants. L’objectif de cette thèse est de déterminer comment l’âge affecte la réponse homéostatique des OL et d’évaluer l’association entre les caractéristiques des ondes en sommeil lent et les performances cognitives chez des personnes d’âge moyen et âgées. La première étude a évalué l’effet de 25 heures d’éveil sur les OL durant un épisode de sommeil de récupération diurne chez de jeunes adultes et des personnes d’âge moyen. Comparativement aux jeunes, les personnes d’âge moyen ont montré une augmentation atténuée de la densité des OL après la privation de sommeil. Elles ont également montré une augmentation plus faible de la synchronisation neuronale durant une OL dans les régions frontales et préfrontales, mesurée par l’amplitude et la pente des OL. La deuxième étude a évalué le lien prédictif des OL, des FS et de l’architecture du sommeil sur les performances à des tests neuropsychologiques mesurant les capacités attentionnelles, les fonctions exécutives et les capacités d’apprentissage verbal chez des participants d’âge moyen et âgés en bonne santé. Seule la fluence verbale était associée à la densité et à la pente des OL. Les OL ne semblent donc pas constituer un marqueur stable du fonctionnement cognitif. Comparativement aux OL, les caractéristiques des FS étaient associées de façon plus systématique aux performances cognitives et plus particulièrement aux capacités d’apprentissage et aux fonctions attentionnelles. Dans l’ensemble, cette thèse suggère que l’augmentation plus faible de la synchronisation neuronale dans les régions antérieures après une privation de sommeil est expliquée par une plasticité synaptique réduite chez les personnes d’âge moyen comparativement aux jeunes. Par ailleurs, la capacité à générer une activité neuronale synchronisée, mesurée par les OL, ne prédit ni la capacité à maintenir le sommeil durant le jour, ni les fonctions cognitives de façon consistante. Les FS, quant à eux, représentent un meilleur marqueur du fonctionnement cognitif au cours du vieillissement normal. Les FS pourraient refléter une meilleure intégrité anatomique/physiologique des réseaux neuronaux impliqués dans les capacités attentionnelles et d’apprentissage.

Morningness-eveningness and sleep habits among adolescents : Age and gender differences.

Resumen tomado de la publicaci??n

Medical Students Circadian Sleep Rhythms and Academic Performance

Objective: to evaluate, with a preliminary study, the distribution of circadian rhythms, sleep schedule patterns and their relationship with academic performance on medical students. Methodology: in this descriptive study, a 10 item original questionnaire about sleep rhythms and academic performance was applied to medical students from different semesters. Week (class time) and weekend schedules, preferences, daytime somnolence and academic performance were asked. Three chronotypes (morningness, intermediate and eveningness) were defined among waking-sleeping preference, difficulty to sleep early, exam preparation preference hour and real sleep schedule. The sleep hour deficit per week night was also calculated. Results: Of the 318 medical students that answered the questionnaire, 62.6% corresponded to intermediate chronotypes, 8.8% to evening-type and 28.7% to morning-type. Significant difference was found among the two chronotype tails (p=0.000, Chi-square 31.13). No correlation was found between academic performance and age, sex, chronotype, week sleep deficit and sleep hours in week and weekends. A 71.1% of the students slept 6 or fewer hours during class time and 78% had a sleep deficit (more frequent in the evening chronotype). Conclusions: No relation was found between sleep chronotype and academic performance. Students tend to morningness. Few studies have been made on equatorial zones or without seasons

Sleep quality perception in youth population

To assess sleep habits and sleep quality perception in a Colombian and Mexican youth sample. Materials and methods: following a sleep diary methodology with a questionnaire of 27 categorical and quantitative items, the assessment was done immediately upon awakening. Results: it was applied to 317 high school (n= 189) and undergrads (n= 128) in Bogotá, Colombia (n= 197) and México City, México (n= 120); 147 females (46,4%) and 170 males (53,6%). The mean age was 18,6 ± 2,81 years with a median and mode of 17 years. The Cronbach’s alpha obtained from 135 measurements during the study period was 0,86 and 0,57 from the mean values of 27 scale items. An inverse correlation was found between hours of sleep per night and number of naps (r= -0,12; p= 0,029); 38% of participants did not nap and slept on average 7,6 night hours or more (X2= 2,78; p= 0,047). The men took more naps than women (men 76,5%; women 55,6%; X2= 15,26; p= 0,000). A reduction of hours of sleep per night and the need for naps was significantly associated with participants’ gender. The mean and median hours of sleep per night (7,2 hours) was used to classify the population into two groups: sleep (+) 7,3 or more hours and sleep (-) 7,2 hours or less. These groups were compared. Conclusions: youth population evaluated showed a reduction of hours of sleep per night was found. This was associated to naps frequency and participant gender.

Can't you sleep, little bear?

El osito no puede dormir pues tiene miedo a la oscuridad aunque el papá Oso le ha colocado un gran farol encendido sobre la cama para que no se asuste. El Gran Oso encuentra una ingeniosa manera de tranquilizarlo.

Can't you sleep, little bear?

El osito no puede dormir pues tiene miedo a la oscuridad aunque el papa Oso le ha colocado un gran farol encendido sobre la cama para que no se asuste. El Gran Oso encuentra una ingeniosa manera de tranquilizarlo. Existe un libro para el alumno con el mismo título en formato pequeño. .

Evaluating effects of aromatherapy massage on sleep in children with autism: a pilot study

Previous studies have found beneficial effects of aromatherapy massage for agitation in people with dementia, for pain relief and for poor sleep. Children with autism often have sleep difficulties, and it was thought that aromatherapy massage might enable more rapid sleep onset, less sleep disruption and longer sleep duration. Twelve children with autism and learning difficulties (2 girls and 10 boys aged between 12 years 2 months to 15 years 7 months) in a residential school participated in a within subjects repeated measures design: 3 nights when the children were given aromatherapy massage with lavender oil were compared with 14 nights when it was not given. The children were checked every 30 min throughout the night to determine the time taken for the children to settle to sleep, the number of awakenings and the sleep duration. One boy's data were not analyzed owing to lengthy absence. Repeated measures analysis revealed no differences in any of the sleep measures between the nights when the children were given aromatherapy massage and nights when the children were not given aromatherapy massage. The results suggest that the use of aromatherapy massage with lavender oil has no beneficial effect on the sleep patterns of children with autism attending a residential school. It is possible that there are greater effects in the home environment or with longer-term interventions.

Maternal psychosocial adversity and the longitudinal development of infant sleep

Research has identified associations between indicators of social disadvantage and the presence of child sleep problems. We examined the longitudinal development of infant sleep in families experiencing high (n = 58) or low (n = 64) levels of psychosocial adversity, and the contributions of neonatal self-regulatory capacities and maternal settling strategies to this development. Assessments of infant sleep at 4-, 7-, and 12-weeks postpartum indicated no differences in sleeping difficulties between high- and low-adversity groups. However, more infant sleep difficulties were reported in the high- versus low-adversity groups at 12- and 18-month follow-ups. Neonatal self-regulatory capacities were not related to the presence or absence of adversity, or to subsequent infant sleep quality. However, there were group differences in maternal settling strategies that did predict subsequent infant sleep difficulties. The pattern of sleep disturbance observed in association with maternal psychosocial adversity at 18-months was consistent with risk for broader impairments in child functioning.

The relationship between parent and child dysfunctional beliefs about sleep and child sleep

Cognitive theories emphasise the role of dysfunctional beliefs about sleep in the development and maintenance of sleep-related problems (SRPs). The present research examines how parents' dysfunctional beliefs about children's sleep and child dysfunctional beliefs about sleep are related to each other and to children's subjective and objective sleep. Participants were 45 children aged 11 -12 years and their parents. Self-report measures of dysfunctional beliefs about sleep and child sleep were completed by children, mothers and fathers. Objective measures of child sleep were taken using actigraphy. The results showed that child dysfunctional beliefs about sleep were correlated with father (r=.43, p<.05) and mother (r=.43, p<.05) reported child SRPs, and with Sleep Onset Latency (r=.34, p<.05). Maternal dysfunctional beliefs about child sleep were related to child SRPs as reported by mothers (r=.44, p<.05), and to child dysfunctional beliefs about sleep (r=.37, p<.05). Some initial evidence was found for a mediation pathway in which child dyfunctional beliefs mediate the relationship between parent dysfunctional beliefs and child sleep. The results support the cognitive model of SRPs and contribute to the literature by providing the first evidence of familial aggregation of dysfunctional beliefs about sleep.

A longitudinal study of child sleep in high and low risk families: relationship to early maternal settling strategies and child psychological functioning

Objectives To investigate whether sleep disturbances previously found to characterise high risk infants: (a) persist into childhood; (b) are influenced by early maternal settling strategies and (c) predict cognitive and emotional/behavioural functioning. Methods Mothers experiencing high and low levels of psychosocial adversity (risk) were recruited antenatally and longitudinally assessed with their children. Mothers completed measures of settling strategies and infant sleep postnatally, and at 12 and 18 months, infant age. At five years, child sleep characteristics were measured via an actigraphy and maternal report; IQ and child adjustment were also assessed. Results Sleep disturbances observed in high-risk infants persisted at five years. Maternal involvement in infant settling was greater in high risk mothers, and predicted less optimal sleep at five years. Poorer five year sleep was associated with concurrent child anxiety/depression and aggression, but there was limited evidence for an influence of early sleep problems. Associations between infant/child sleep characteristics and IQ were also limited. Conclusions Early maternal over-involvement in infant settling is associated with less optimal sleep in children, which in turn, is related to child adjustment. The findings highlight the importance of supporting parents in the early development of good settling practices, particularly in high-risk populations.

"When I go to bed hungry and sleep, I'm not hungry": children and parents' experiences of food insecurity

Evidence demonstrates food insecurity has a detrimental impact on a range of outcomes for children, but little research has been conducted in the UK, and children have rarely been asked to describe their experiences directly. We examined the experiences of food insecure families living in South London. Our mixed-methods approach comprised a survey of parents (n = 72) and one-to-one semi-structured interviews with children aged 5-11 years (n = 19). The majority of parents (86%) described their food security during the preceding year as very low. Most reported they had often or sometimes had insufficient food, and almost all had worried about running out of food. Two thirds of parents had gone hungry. Most parents reported they had been unable to afford a nutritionally balanced diet for their children, and just under half reported that their children had gone hungry. Four themes emerged from the interviews with children: sources of food; security of food, nutritional quality of food, and experiences of hunger. Children's descriptions of insufficient food being available indicate that parents are not always able to shield them from the impact of food insecurity. The lack of school-meals and after-school clubs serving food made weekends particularly problematic for some children. A notable consequence of food insecurity appears to be reliance on low-cost takeaway food, likely to be nutritionally poor.