The basic principles of normal sleep are the same for children and adults. Normal sleep can be simply described as the ability to fall asleep easily, sleep through the night, and wake up feeling refreshed.
Long-term longitudinal data have been published by Iglowstein et al. (12) to illustrate the developmental course and age-specific variability of sleep patterns. As part of the Zurich Longitudinal Studies, they followed 493 children for 16 years. The study used structured sleep-related questionnaires at 1, 3, 6, 9, 12, 18, and 24 months after birth and then at annual intervals until 16 years of age. Total sleep duration decreased from an average of 14.2 hours [standard deviation (SD) = 1.9 hours] at six months of age to an average of 8.1 hours (SD=0.8 hours) at 16 years of age. Total sleep duration decreased across the studied cohorts (1974-1993) because bedtime became later, but wake time remained essentially unchanged. Between 1.5 years and 4 years of age, there was a prominent decline in napping habits. At 1.5 years of age 96.4% of children had naps; by four years of age only 35.4% napped.
This is consistent with a prior study of napping patterns by Weissbluth (13). Napping patterns were monitored in a cohort of 172 children followed from six months to seven years of age. There were no differences in the number of naps at six months of age or the pattern of napping based on gender, birth order, and whether naps disappeared spontaneously or were stopped by the parents. Total daytime sleep remained a stable individual characteristic between 6 and 18 months of age. A pattern of two naps per day was well-established by 9 to 12 months of age and one afternoon nap by 15 to 24 months. The duration of naps from two to six years was two hours. During the third and fourth year, napping occurred in the majority of children, but at decreasing rates. A minority of children was napping by five to six years and naps usually disappeared by age seven. If a child continues to nap by the age of seven years, it is possible that a sleep disorder may be present. Naps may not be called naps but rather reported as falling asleep while riding home from school.
However, napping behavior must be put into a cultural and possibly racial context. It would be less concerning if napping or "siestas" are part of the child's cultural environment. A more recent survey of napping patterns reported remarkable racial differences in reported napping and night-time sleep patterns beginning as early as age three and extending to at least eight years of age (14). In this study a more gradual age-related decline in napping was found for black children. At age 8, 39.1% of black children were reported to nap, compared with only 4.9% of white children. Black children also napped significantly more days per week, had shorter average nocturnal sleep durations, and slept significantly less on weekday nights than on weekend nights. Despite differences in sleep distribution, total weekly sleep duration (diurnal and nocturnal) was nearly identical for the two racial groups at each year of age.
The information on sleep and napping patterns is usually obtained from parental report. A study from Brown University combined parental sleep diaries with objective information from actigraphy (15). This study consisted of 169 normal children from 12 months to 60 months of age. This cross-sectional sample of children wore actigraphs for one week while their mothers kept concurrent diaries. Bedtimes and sleep start times were earliest, and time in bed and sleep period times were longest for 12-month-old children. Rise time, sleep end time, and nocturnal sleep minutes did not differ across age groups. Actigraphic estimates indicated that children aged one to five years slept an average of 8.7 hours at night. Actigraph-based nocturnal wake minutes and wake bouts were higher than maternal diary reports for all age groups. Daytime naps decreased across age groups and accounted for most of the difference in 24-hour total sleep over age groups. Children in families with lower socioeconomic status had later rise times, longer time in bed, more nocturnal wake minutes and bouts, and more night-to-night variability in bedtime and sleep period time. Not surprisingly, this study reported children with longer naps slept less at night.
In adults and most children, rapid eye movement (REM) periods occur in cycles of approximately 90 minutes throughout the night. REM latencies may be longer in younger children (16). New data suggest that the length of the REM/non-REM (NREM) cycle fluctuates with age (17). At the end of every REM cycle there is usually an arousal or brief awakening. In infants REM cycles are shorter (approximately 40-60 minutes). Parents may be concerned that their infant seems to "wake up every hour." These brief awakenings may be part of the child's normal rhythm but an overly attentive parent may inadvertently reinforce and prolonged the awakenings. On the other hand, it is possible that the child's awakenings are due to a condition that is exacerbated by REM sleep such as OSA. The percent of the total sleep time spent in REM decreases from birth when it may take up 50% of the total sleep time to approximately 20% at three years of age. It remains at this percent throughout adulthood.
Delta or slow-wave sleep represents our deepest sleep as measured by the arousal threshold (amount of stimulation needed to wake up the sleeper). Delta sleep has homeostatic properties: it increases in duration and intensity in response to sleep deprivation. The amount of delta sleep is at least 10% of the total sleep time in children and decreases after adolescence. It clusters in the first third of the night. During delta sleep it is extremely difficult to arouse children. If aroused, they often appear disoriented and cognitively slowed. Parasomnias such as sleepwalking and sleep terrors usually emerge from slow-wave sleep and in children commonly occur in the first third of the night.
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A Guide to Natural Sleep Remedies. Many of us experience the occasional night of sleeplessness without any consequences. It is when the occasional night here and there becomes a pattern of several nights in arow that you are faced with a sleeping problem. Repeated loss of sleep affects all areas of your life The physical, the mental, and theemotional. Sleep deprivation can affect your overall daily performance and may even havean effecton your personality.