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Physiology of sleep. M Maldonado MD. Sleep during infancy. Neonate can sleep 18 hours during a 24 hour period During the first year of life the sleep period may be reduced to 12 hours Infant may have up to 50% of REM SLEEP or more , while adults have 20%
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Physiology of sleep M Maldonado MD
Sleep during infancy • Neonate can sleep 18 hours during a 24 hour period • During the first year of life the sleep period may be reduced to 12 hours • Infant may have up to 50% of REM SLEEP or more , while adults have 20% • Sleep cycles are shorter than in the adult, 50-60 min • Cycles can start with REM sleep. REM is controlled by a more primitive center, brainsteam.
Neonatal “states” • Prechtl and Beintame. Then Brazelton described them • Six “states” that are cyclical. One is “active sleep” (REM) and the other is “quiet sleep” (non REM) • Sleep cycles controlled by suprachiasmatic nucleus in hypothalamus
Infant sleep? • Purpose of sleep? Sleep is an activity with distinctive features, not just absence of awake state • Visual development (REM sleep), neuronal migration? • Circadian rhythm. Perception of light and darkness establish a pattern • Homeostatic need for rest accumulates through the day, leading to sleep.
Physiology • REM is mediated by brainstem, through a cholinergic system • Non-REM is mediated by the locus coeruleus of the brainstem and the messenger is adrenaline • There may be a homeostatic load through the day that makes the need for rest imperative • There are light/darkness cues perceived in the suprachiasmatic nucleous (hypothalamus)
Physiology • Sleep deprivation leads to an increased “sleep pressure” ( need for sleep) • In neonate the slightest deprivation leads to increased sleep pressure, then greater duration of non Rem (quiet ) sleep • What is the “zeitgeber”? Of sleep cycles • The night/day rhythmicity starts to be observed at 3 months of age
Physiology • Gradually the proportion of quiet sleep *non REM increases • At about 3 months, sleep episodes are initiated now by quiet sleep *non REM
Sleep in the preschool child • Longer periods of sleep during the night • Importance of separation anxiety for sleep onset • Fear of monsters and other dangerous creatures • Death fears • Waking up during the night • Onset of report of dreams, and of nightmares • More frequently sleep walking and sleep terror
Sleep during school-age • Teh child requires 9 to 10 hours of sleep • More interest in staying up late • Worries about school, examinations, what will happen next day • Fear of thieves, kindpannings, fires, earthquakes, tornadoes, etc. • Shame of admitting to fears
Sleep in the adolescent • Increase in the need for sleep,more hours • Frequently problems with sleep onset • Going to bed later • Difficulties to get up in the morning • Multiple demands for the youngster:school, homework, work, social functions, parties,etc..