Sleep Need in Children
William Wilkoff, MD, FAAPBowdoin Medical Group
Brunswick, ME 04011, USA
To the Editor.—
As a pediatrician in general practice, I am drawn to any article that promises me help in dealing with the hundreds of patients with sleep problems that I see each year. However, I found the article by Iglowstein and his colleagues1 disappointing and confusing.
I can’t quarrel with their methods, but I’m not sure I can use their data to "reassure parents of the normality of their child’s sleep duration." This would be like reassuring a parent whose 4-year-old watches 3 hours of television each day that the child is normal because most of the other 4-year-olds I know are watching at least that much. Just because the majority is doing something (or not doing something, in the case of sleep) doesn’t make it healthy.
My practice is full of children who aren’t getting enough sleep. Many of the teenagers are depressed. The toddlers are cranky to the point of tantrums. Some children have trouble attending in school, and others have nocturnal leg pains and migraine headaches aggravated by sleep deprivation. Most parents I know underestimate the sleep needs of their children.
The authors have observed that total sleep duration decreased across the studied cohorts from 1974 to 1993. I’m sure no one is surprised that this change was the result of increasingly later bedtimes and unchanged wake up times. Unfortunately, we are left to assume that this shift is normal and the result of "a more liberal parental attitude toward bedtime." Its causes are far more complex, and the results of the sleep deprivation it is creating are not trivial.
I would like to thank the authors for collecting these data that confirm what primary care pediatricians have assumed for years. What we need now is another large cohort study that examines sleep need using a more valid assessment such as sleep latency.
REFERENCE
- Iglowstein I, Jenni OG, Molinari L, Largo RH. Sleep duration from infancy to adolescence: reference values and generational trends.
Pediatrics.2003; 111
:302
–307
[Abstract/Free Full Text]
Oskar G. Jenni, MD
Ivo Iglowstein, MD
Luciano Molinari, MD
Remo H. Largo, MD
Department of Psychiatry and Human Behavior
Brown Medical School
Providence, RI 02915, USA
Growth and Development Center
University Children’s Hospital Zurich
8032 Zurich, Switzerland
In Reply.—
We appreciate the letter from Dr Wilkoff following our article1 and the opportunity to address several important issues. The principal aim of our article was to demonstrate the large variability in parent-reported sleep duration in children and to underscore that the optimal amount of sleep in the individual child cannot be determined without taking his age and individual sleep need into account. A recent study indicates that the variability of habitual sleep duration may have a physiological basis. Aeschbach et al2 demonstrated that the individually programmed circadian pacemaker exerts considerable influence on adult sleep duration. We agree with their conclusion that it may not be possible to define one single "healthy" sleep duration for the entire population and believe that individual differences in "sleep need" should also occur in children. Differences in sleep duration as a function of development add to the complexity determining sleep need in children.
Although we used the terms "sleep duration" interchangeably with "sleep need," we do not know whether this is indeed accurate. Dr Wilkoff raises concerns that "many children in his practice do not get enough sleep" and points to the unresolved issue of defining and assessing sleep need in children. How much sleep is enough to avoid adverse outcomes for health, development, and behavior? Sleep need much as other biological variables during development (eg, growth3) is likely to vary among children, as is their response to sleep deprivation. Better measures and experimental paradigms are required to more adequately ascertain individual sleep need not only in children but in adults as well. However, the issue is far more complex than just measuring sleep latency, an objective indicator for daytime sleepiness.4 Until we have objective, cost-effective measures for individual sleep need in clinical practice, we must continue to rely on sleep diaries, parental reports, and existing normative values. Our article adds additional normative data to the literature.
Dr Wilkoff describes "depressed teenagers, cranky toddlers, and children with school difficulties due to sleep loss." These children have to be assessed for the causes of their abnormal daytime behavior, for which excessive daytime sleepiness may be one of several possible explanations. We do not agree, however, that "most parents underestimate the sleep needs of their children." Rather, clinicians commonly find that parents overestimate the time in bed required by their children, which may cause abnormal nocturnal behavior, such as bedtime resistance or night wakings, particularly in younger children.5–7 In these cases, sleep time needs to be consolidated and, therefore, the percentiles are helpful to convince parents of the normality of their child’s sleep duration.
The timing of sleep and wake is controlled not only by societal pressure (eg, parental control) but by biological processes as well.8 Increased understanding of the general biological mechanisms of sleep regulation (circadian and homeostatic) coupled with the incorporation of individual differences in these processes will help us to better meet the needs of children. A child with evening circadian phase preference ("owl") will likely resist early bedtime but will fall asleep when his or her requirement for later bedtime is adequately considered. Applying general rules for bedtime regardless of individual and age-related differences is inappropriate.
The increase in more child-oriented attitudes of parents toward evening bedtime may be one reason among others for the reported increased delay of bedtime and the decline in sleep duration across generations. In the same sample of children, we observed considerably less bedtime resistance in later than in earlier cohorts, indicating that parents in the 1990s may have adjusted bedtime to their children’s actual sleep need more appropriately than parents in the 1970s.9 Significant cultural differences in child-rearing practices and in the daily lives of children and teenagers, however, may make this explanation less suitable for American than for Swiss children.
REFERENCES
- Iglowstein I, Jenni OG, Molinari L, Largo RH. Sleep duration from infancy to adolescence: reference values and generational trends. Pediatrics.2003; 111 :302 –307
- Aeschbach D, Sher L, Postolache TT, Matthews JR, Jackson MA, Wehr TA. A longer biological night in long sleepers than in short sleepers.
J Clin Endocrinol Metab.2003; 88
:26
–30
[Abstract/Free Full Text] - Prader A, Largo RH, Molinari L, Issler C. Physical growth of Swiss children from birth to 20 years of age. First Zurich longitudinal study of growth and development. Helv Paediatr Acta Suppl.1989; 52 :1 –125[Medline]
- Fallone G, Owens J, Deane J. Sleepiness in children and adolescents: clinical implications. Sleep Med Rev.2002; 6 :287 –306[CrossRef][Web of Science][Medline]
- Largo RH, Hunziker UA. A developmental approach to the management of children with sleep disturbances in the first three years of life. Eur J Pediatr.1984; 142 :170 –173[CrossRef][Web of Science][Medline]
- Galofre I, Santacana P, Ferber R. The "tib>tst" syndrome. A cause of wakefulness in children [abstract]. Sleep Res.1992; 21 :199
- Ferber R. Circadian rhythm sleep disorders in childhood. In: Ferber R, Kryger M, eds. Principles and Practice of Sleep Medicine in the Child. Philadelphia, PA: WB Saunders Co; 1995
- Borbély A, Achermann P. Sleep homeostasis and models of sleep regulation. In: Kryger M, Roth T, Dement W, eds. Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, PA: WB Saunders Co; 2000:377–390
- Jenni OG, Zinggeler Fuhrer H, Iglowstein I, Molinari L, Largo RH. Cosleeping and sleep problems among Swiss children in the first 10 years of life: prevalence, correlations and secular trends [abstract]. Sleep.2003 . In press
PEDIATRICS (ISSN 1098-4275). ©2003 by the American Academy of Pediatrics
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