Normal Sleep Patterns in Infants and Children: A Systematic Review of Observational Studies

Galland, B. C., Taylor, B. J., Elder, D. E., & Herbison, P. (2012). Normal sleep patterns in infants and children: A systematic review of observational studies. Sleep Medicine Reviews, 16(3), 213-222.

More research is needed to identify normal sleep patterns in breastfed versus bottle-fed infants, in toddlers, on weekdays versus weekends, and as related to gender and ethnic differences. What is known is that children sleep longer at night and experience fewer night-wakings and daytime naps as they develop.

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Sample

  • N: 34 articles
  • Search Method: An extensive literature search of five electronic databases was conducted: Ovid MEDLINE, Web of Science, CINAHL, Scopus, and PsycINFO. All databases were searched for relevant articles published from 1990 to 2010 in which the title, abstract or keywords included reference to sleep and infant (age 0 to 23 months), or preschool (age 2 to 5 years) or child (age 6 to 12 years), and diary or questionnaires or actigraphy. The search was limited to English-language articles. Titles and abstracts were examined to extract potentially relevant articles and subsequently examined in more depth for inclusion/exclusion criteria by the main author and the research assistant.
  • Inclusion Criteria: Studies were required to fulfill the following criteria: a) original article; b) prospective cohort design; c) non-clinic studies; d) participants aged 0 to 12 years; e) sample was well-described (e.g., number of subjects, gender, recruitment criteria, etc.); f) include one or more of the following variables of interest: sleep duration, sleep latency, number of night wakings, longest sleep period, number of daytime sleeps; g) data for variables of interest were presented numerically with a measure of central tendency and variance.
  • Exclusion Criteria: Studies were excluded if: a) case-control design was used; b) the work was published as a dissertation or abstract only; c) if more than one report from the same study was published, we included only the first publication with data meeting the inclusion/exclusion criteria.

Objective

  1. To provide a standard against which abnormal sleep patterns can be measured, to in turn inform policy and strategies for intervention and to contribute to and advance our knowledge regarding developmental patterns of sleep.

Design—Meta analysis

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Findings

  1. Sleep patterns show the following developmental trends for sleep: Duration decreases from 0 to 12 years, number of night-wakings decreases from 0 to 2 years, longest sleep period increases from 0 to 2 years, and number of daytime naps decreases up to age 2.
  2. Sleep duration is the most commonly reported sleep variable. It has a wide range in infancy with the greatest rate of change occurring within the first 6 months of life.
  3. Predominantly Asian countries report less sleep duration than non-Asian countries.
  4. A clear omission from nearly all the infant studies is a breakdown of breastfeeding or bottle-feeding, well known to influence sleep patterns.
  5. There are several aspects of sleep that have limited documentation: normal sleep patterns in the toddler age group, gender and ethnic differences, and weekday versus weekend differences across all age groups.
  6. Studies publishing information on sleep patterns should present numerical data with measures of central tendency and variability so data can be incorporated into meta-analysis.

Limitations

  • The findings of this review need to be validated against parental reports matched to objective measures of the same sleep variables.
  • More prospective, large-scale longitudinal studies, rather than cross-sectional studies, are required to provide richer sources of data to document developmental patterns of sleep.
  • Research around cultural practices influencing sleep development is needed to provide culture-specific data.
  • The gap in the literature around the toddler age group suggests this age needs to be targeted to better document normal sleep patterns before children’s daytime routine is changed to fit school schedules.
  • The significance of the lower and upper limits of our data as cut-offs for problematic sleep need to be assessed for clinical application.