Interactions entre le sommeil, l’attention et le contrôle postural chez des sujets jeunes et âgés

Les pertes d’équilibre représentent une cause importante de blessure et de mortalité, notamment sur le milieu du travail et chez les personnes âgées. Cette thèse explore les effets du manque de sommeil sur le contrôle postural en fonction de l’âge et s’intéresse à l’influence des ressources attentionnelles, perceptuelles et motrices sur la relation entre le sommeil et le contrôle postural. Des sujets jeunes et âgés ont effectué diverses tâches posturales statiques sur des plates-formes de force après une nuit de sommeil et après 25 heures de privation de sommeil. L’étendue et la vitesse des déplacements du centre de pression ont été mesurées en gardant les yeux ouverts et les yeux fermés sous trois niveaux de charge cognitive. Les résultats montrent que la privation de sommeil a augmenté l’étendue du centre de pression dans les deux groupes d’âge et a augmenté la vitesse du centre de pression chez les sujets âgés. De plus, les effets de la privation de sommeil sur le contrôle postural étaient davantage prononcés lorsque les sujets âgés gardent les yeux fermés. L’augmentation de la charge cognitive sous privation de sommeil a poussé la majorité des sujets jeunes à adopter un contrôle postural plus statique, alors que chez les sujets âgés, les effets de la charge cognitive ne se surajoutaient pas à ceux de la privation de sommeil. Ces observations suggèrent que la privation de sommeil ait des effets déstabilisateurs sur le contrôle postural qui sont plus marqués chez les personnes âgées, surtout lorsque les informations visuelles sont altérées. Il est donc proposé que le manque de sommeil soit un facteur de risque significatif pour les chutes.Falls are an important cause of injuries and mortality, especially in the work force and in the elderly population. This thesis investigates the effects of sleep loss on postural control according to age and explores the influence of attentional, perceptual and motor resources on the relationship between sleep and postural control. Young and older participants completed various postural tasks on force plates after a night of sleep and after 25 hours of sleep deprivation. Center of pressure range and velocity were measured with eyes open and with eyes closed while participants performed an interference task, a control task, and no cognitive task. Sleep deprivation increased the range of center of pressure in both age groups and center of pressure speed in older participants only. Moreover, in elderly participants, the destabilizing effects of sleep deprivation were more pronounced with eyes closed. The interference task brought younger participants to adopt a more static postural strategy when sleep deprived. However, in older participant, the interference task did not alter postural control beyond the destabilization induced by sleep loss. These observations suggest that sleep loss has greater destabilizing effects on postural control in older than in younger adults, especially when vision is altered. It is therefore proposed that sleep debt may be a significant risk factor for falls

Aging worsens the effects of sleep deprivation on postural control.

Falls increase with age and cause significant injuries in the elderly. This study aimed to determine whether age modulates the interactions between sleep deprivation and postural control and to evaluate how attention influences these interactions in the elderly. Fifteen young (24±2.7 y.o.) and 15 older adults (64±3.2 y.o.) stood still on a force plate after a night of sleep and after total sleep deprivation. Center of pressure range and velocity were measured with eyes open and with eyes closed while participants performed an interference task, a control task, and no cognitive task. Sleep deprivation increased the antero-posterior range of center of pressure in both age groups and center of pressure speed in older participants only. In elderly participants, the destabilizing effects of sleep deprivation were more pronounced with eyes closed. The interference task did not alter postural control beyond the destabilization induced by sleep loss in older subjects. It was concluded that sleep loss has greater destabilizing effects on postural control in older than in younger participants, and may therefore increase the risk of falls in the elderly

Impacts of Age and Sleep on Postural Control Variables.

<p>Results of the two-way ANOVA (2 age groups by 2 sleep pressure conditions) with eyes open and no cognitive task. Significant effects and interactions are shown in bold.</p

Interactions Between Sleep and Vision/Cognitive Load in the Older Group.

<p>Older participants' means and SEM for each postural parameter after sleep (black line) and after sleep deprivation (dotted line). Left panels (A to D): Effects of sleep deprivation in each visual state (with eyes open and eyes closed; * p<0.05, ** p<0.01). Right panels (E to H): Effects of sleep deprivation in each cognitive load (when not performing any task (NoTask), the control task (Ctrl) and the interference task condition (Interf); * p<0.05, ** p<0.01).</p

Age Modulation of the Effects of Sleep Loss on Postural Control.

<p>Means and SEM for each postural parameter after sleep (Sleep) and after sleep deprivation (SD) for the young group (n = 15; grey line) and the older group (n = 15; black line). * p<0.05, ** p<0.01.</p

Wearable Technologies for Developing Sleep and Circadian Biomarkers: A Summary of Workshop Discussions

The \u27International Biomarkers Workshop on Wearables in Sleep and Circadian Science\u27 was held at the 2018 SLEEP Meeting of the Associated Professional Sleep Societies. The workshop brought together experts in consumer sleep technologies and medical devices, sleep and circadian physiology, clinical translational research, and clinical practice. The goals of the workshop were: 1) characterize the term wearable for use in sleep and circadian science, and identify relevant sleep and circadian metrics for wearables to measure; 2) assess the current use of wearables in sleep and circadian science; 3) identify current barriers for applying wearables to sleep and circadian science; and 4) identify goals and opportunities for wearables to advance sleep and circadian science. For the purposes of biomarker development in the sleep and circadian fields, the workshop included the terms wearables , nearables , and ingestibles . Given the state of the current science and technology, the limited validation of wearable devices against gold standard measurements is the primary factor limiting large-scale use of wearable technologies for sleep and circadian research. As such, the workshop committee proposed a set of best practices for validation studies and guidelines regarding how to choose a wearable device for research and clinical use. To complement validation studies, the workshop committee recommends the development of a public data repository for wearable data. Finally, sleep and circadian scientists must actively engage in the development and use of wearable devices to maintain the rigor of scientific findings and public health messages based on wearable technology

Lower In vivo Myo-Inositol in the Anterior Cingulate Cortex Correlates with Delayed Melatonin Rhythms in Young Persons with Depression

Myo-inositol, a second messenger glucose isomer and glial marker, is potentiated by melatonin. In addition to common abnormalities in melatonin regulation, depressive disorders have been associated with reduced myo-inositol in frontal structures. This study examined associations between myo-inositol in the anterior cingulate cortex and the timing of evening melatonin release. Forty young persons with unipolar depression were recruited from specialized mental health services (20.3 ± 3.8 years old). Healthy controls were recruited from the community (21.7 ± 2.6 years old). The timing of dim light melatonin onset (DLMO) was estimated using salivary melatonin sampling. Myo-inositol concentrations (MI/CrPCr ratio) in the anterior cingulate cortex were obtained using proton magnetic resonance spectroscopy. After controlling for age, sex, and CrPCr concentration the depression group had significantly lower MI/CrPCr ratios than healthy controls [F(4, 75) = 11.4, p = 0.001]. In the depression group, later DLMO correlated with lower MI/CrPCr ratio (r = −0.48, p = 0.014). These findings suggest that neurochemical changes in the frontal cortex are associated with circadian disruptions in young persons with depression

The Relationship between Sleep-Wake Cycle and Cognitive Functioning in Young People with Affective Disorders

<div><p>Although early-stage affective disorders are associated with both cognitive dysfunction and sleep-wake disruptions, relationships between these factors have not been specifically examined in young adults. Sleep and circadian rhythm disturbances in those with affective disorders are considerably heterogeneous, and may not relate to cognitive dysfunction in a simple linear fashion. This study aimed to characterise profiles of sleep and circadian disturbance in young people with affective disorders and examine associations between these profiles and cognitive performance. Actigraphy monitoring was completed in 152 young people (16–30 years; 66% female) with primary diagnoses of affective disorders, and 69 healthy controls (18–30 years; 57% female). Patients also underwent detailed neuropsychological assessment. Actigraphy data were processed to estimate both sleep and circadian parameters. Overall neuropsychological performance in patients was poor on tasks relating to mental flexibility and visual memory. Two hierarchical cluster analyses identified three distinct patient groups based on sleep variables and three based on circadian variables. Sleep clusters included a ‘long sleep’ cluster, a ‘disrupted sleep’ cluster, and a ‘delayed and disrupted sleep’ cluster. Circadian clusters included a ‘strong circadian’ cluster, a ‘weak circadian’ cluster, and a ‘delayed circadian’ cluster. Medication use differed between clusters. The ‘long sleep’ cluster displayed significantly worse visual memory performance compared to the ‘disrupted sleep’ cluster. No other cognitive functions differed between clusters. These results highlight the heterogeneity of sleep and circadian profiles in young people with affective disorders, and provide preliminary evidence in support of a relationship between sleep and visual memory, which may be mediated by use of antipsychotic medication. These findings have implications for the personalisation of treatments and improvement of functioning in young adults early in the course of affective illness.</p></div