SECTION 2 - RESTRICTED SLEEP: NEUROBEHAVIORAL AND PHYSIOLOGICAL EFFECTS

Sleep Deprivation in Children and Adolsescents

Background

Many fundamental questions regarding basic physiologic processes mediating sleepiness and alertness and the neurobiological processes underlying the cumulative neurobehavioral effects of chronic and intermittent sleep restriction are important in understanding their effects on the developing brain. Very little is known about the extent to which the relative plasticity of neural systems in children affects their vulnerability to adverse neurobehavioral, cognitive, emotional and physical consequences of sleep loss, and how sleep restriction impacts upon a variety of neurodevelopmental processes.

Compared to adults, little is known about the magnitude and distribution, causes, consequences, and assessment of sleep loss and sleepiness in children and adolescents. Because the neurobehavioral manifestations of sleepiness in children may differ substantially from those of adults, the first challenge is to operationally define sleepiness in children. Objective, reliable, and cost-effective measures of sleepiness and alertness in children are lacking-particularly measures that could be applied to large epidemiological samples. In addition, subjective self-report data regarding sleepiness are largely unavailable in children, and behavioral manifestations of sleepiness not only vary with age and developmental level but also are often not reliably interpreted by parents and other caretakers.

Empirical studies involving both normal and sleep-deprived pediatric populations (e.g., children with sleep disorders, adolescents) have described the extent and consequences of inadequate or disrupted sleep in children. A few studies have examined mood, behavior, and performance changes resulting from acute sleep loss in children in experimental settings, but results have been inconsistent. Profiles of neurobehavioral and cognitive deficits related to chronic sleep loss and cumulative sleep debt in children are even less well defined, and little is known about the functional impairments that can develop in "real world" activities such as school performance, social relationships and behavior at home, and extracurricular and safety-sensitive activities (e.g., sports, driving).

Furthermore, few studies have attempted to use neuroimaging or metabolic techniques in children and adolescents to correlate changes secondary to sleep loss with alterations in specific brain functions known to occur in adults, e.g., complex tasks modulated by the prefrontal cortex. Despite potentially important adverse effects of sleep loss on neuroendocrine, metabolic, immunologic, cardiovascular, and other physiologic systems in the developing organism, the relationship between sleepiness and these physiologic parameters in children is largely unexplored.

An additional challenge is to examine variables that may serve as relative risk promoting or protective factors for the effects of sleep loss in children, including those that may be genetically determined. These variables may yield important information about the development of inter-individual differences in vulnerabilities to sleep loss that extend into adulthood. In addition, understanding these variables will allow definition of vulnerable populations, including racial and ethnic minorities and underserved children, in whom early intervention may be necessary for maintenance of health and prevention of long-term sequelae.

Progress In The Last 5 Years

- Epidemiologic studies have begun to explore selected relationships between chronic partial sleep deprivation and sleep disruption related to primary sleep disorders, mood and performance deficits in children and adolescents, and academic failure. Studies of sleep in children with primary behavior and learning problems have further supported an association between sleep restriction and performance impairments. Evidence indicates that children experience significant daytime sleepiness as a result of disturbed or inadequate sleep, and most studies suggest a strong link between sleep disturbance and behavioral problems.

- Studies delineating the neurobehavioral, cognitive, and emotional effects of sleep loss in experimental settings in adolescents and older school-aged children have broadened our understanding of the similarities and differences that exist between adults and children and between children of different ages. Decreased positive mood in association with sleep disturbance is a consistent finding. Neuropsychological profiles of impairment have been less consistent, however, with more reliable effects on attention/response inhibition, and variable effects on motor skills, memory, verbal creativity, problem solving, and general cognitive abilities.

Research Recommendations

- Establish the incidence and prevalence of chronic sleep loss and sleepiness in children using objective, standardized and cost-effective methods of assessing sleepiness and/or its functional consequences at all stages of maturational development. Specific vulnerable and at-risk populations for adverse consequences of sleep loss and sleepiness should be identified, as well as relative risks and protective factors for the expression of sleep deprivation effects. The biological and behavioral factors that result in sleep loss in children and adolescents also need to be identified.

- Identify deficits in specific neuropsychological domains and patterns of impairment resulting from acute and chronic sleep loss in children at various developmental stages, including higher level cognitive processes such as attention, motivation and emotional regulation. Neuroimaging and other novel techniques should be utilized to examine the neurophysiologic effects of sleep loss on cognition and performance in the developing human.

- Examine the bi-directional effects of sleep loss and sleepiness on the immune, neuroendocrinologic and metabolic, cardiovascular, and other physiologic systems, and identify developmentally appropriate biologic markers for the effects of sleep loss.