Secular trends in adult sleep duration: A systematic review

Little evidence exists to support the common assertion that adult sleep duration has declined. We investigated secular trends in sleep duration over the past 40 years through a systematic review.

Systematic search of 5 electronic databases was conducted to identify repeat cross-sectional studies of sleep duration in community-dwelling adults using comparable sampling frames and measures over time. We also attempted to access unpublished or semi-published data sources in the form of government reports, theses and conference proceedings. No studies were excluded based on language or publication date. The search identified 278 potential reports, from which twelve relevant studies were identified for review.

The 12 studies described data from 15 countries from the 1960s until the 2000s. Self-reported average sleep duration of adults had increased in 7 countries: Bulgaria, Poland, Canada, France, Britain, Korea and the Netherlands (range: 0.1–1.7 min per night each year) and had decreased in 6 countries: Japan, Russia, Finland, Germany, Belgium and Austria (range: 0.1–0.6 min per night each year). Inconsistent results were found for the United States and Sweden.

There has not been a consistent decrease in the self-reported sleep duration of adults from the 1960s to 2000s. However, it is unclear whether the proportions of very short and very long sleepers have increased over the same period, which may be of greater relevance for public health.

Table 1. Literature search strategy and number of results for each database.

View Within ArticleTable 2. Summary of included results by country (some studies have multiple results).

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Longitudinal associations between sleep duration and subsequent weight gain: A systematic review

a Doctoral Program in Population Health and Clinical Outcomes Research, Department of Preventive Medicine, HSC Level 3, Stony Brook University, Stony Brook, NY 11794-8338, USAb Department of Preventive Medicine, Graduate Program in Public Health, HSC Level 3, room 071, Stony Brook University, Stony Brook, NY 11794-8338, USAReceived 31 December 2010. Revised 19 May 2011. Accepted 23 May 2011. Available online 23 July 2011.View full text To systematically examine the relationship between sleep duration and subsequent weight gain in observational longitudinal human studies.

Systematic review of twenty longitudinal studies published from 2004–October 31, 2010.

While adult studies (n = 13) reported inconsistent results on the relationship between sleep duration and subsequent weight gain, studies with children (n = 7) more consistently reported a positive relationship between short sleep duration and weight gain.

While shorter sleep duration consistently predicts subsequent weight gain in children, the relationship is not clear in adults. We discuss possible limitations of the current studies: 1) the diminishing association between short sleep duration on weight gain over time after transition to short sleep, 2) lack of inclusion of appropriate confounding, mediating, and moderating variables (i.e., sleep complaints and sedentary behavior), and 3) measurement issues.

prs.rt("abs_end");Sleep; Obesity; Weight gain; Longitudinal studiesBMI, Body mass index; CDC, Centers for Disease Control and Prevention

Figures and tables from this article:

Fig. 1. Illustration of literature search.

View Within ArticleFig. 2. Patel & Hu Model2 with media use added.

View Within ArticleTable 1. Adult studies.

View Within ArticleTable 2. Adult Study Independent Variables.

View Within ArticleTable 3. Children Studies.

View Within ArticleTable 4. Children Study Independent Variables.

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