Normal Sleep in Children and Adolescents

Nam, Sang Ook

Abstract

Sleep is not just a rest for brain activity during daytime, but also has a vital function for memory consolidation after learning as well as restoration of both body and brain. While restoration of the body mainly occurs during non-rapid eye movement (NREM) sleep, especially during slow wave sleep, restoration of brain and memory consolidation occurs mainly during REM sleep. Adenosine acts as a sleep-inducing agent, so called somnogen or hypnotoxin which accumulates while awake. Sleep deprivation results in the disruption of every aspect of physical, cognitive, and behavioral function, which can be reversed only by sleep. Many neurotransmitter-secreting nuclei in the brain stem, hypothalamus, and basal forebrain are key structures for wakefulness, NREM, and REM sleep. They have been localized in the basal forebrain (acetylcholine), ventrolateral preoptic area (VLPO, GABA and galanin), tuberomamillary nucleus (TMN, histamine), lateral and posterior hypothalamus (orexin/hypocretin), reticular formation (glutamate), substantia nigra/ventral tegmental area (SN/VTA, dopamine), pedunculopontine nucleus and lateral dorsal tegmentum (PPT-LDT, acetylcholine), locus ceruleus (norepinephrine), and the raphe nuclei (serotonin). All are activated during wakefulness except VLPO which secrets GABA and galanin, which suppress other nuclei for sleep induction. Acetylcholine-secreting PPT-LDT is a major locus for REM sleep, and is inhibited by the raphe nuclei and locus ceruleus which act as REM-off neurons inducing NREM sleep. The suprachiasmatic nucleus is a pacemaker for circadian rhythms, which can be modified by bright light and melatonin. It should be emphasized that the best performance of cognitive function including reactivity, abstract thinking, creativity, memory, executive function, and accurate and efficient work as well as physical well-being is achieved by sufficient and appropriate sleep.