Sleep duration and mortality in the elderly: a systematic review with meta-analysis

Abstract

ObjectiveThe purpose of our study was to evaluate the association between short and long sleep duration and all-cause and cardiovascular mortality among elderly individuals.DesignSystematic review and meta-analysis of population-based cohort studies.SettingArticles were retrieved from international and national electronic databases.Study selectionStudies were identified in PubMed, EMBASE, LILACS (Latin American and Caribbean Health Sciences Literature), IBECS (Bibliographic Index on Health Sciences from Spain) and CAPES (PhD thesis repository) between 1980 and 2015. Studies which met all criteria were eligible: participants aged 60 years or over, assessment of sleep duration as 24 h, nighttime or daytime sleep, evaluation of all-cause or cause-specific mortality, population-based cohort studies conducted on representative samples. There was no language restriction and studies published as abstracts were excluded.Data extractionData were analysed using the Comprehensive Meta-Analysis software (V.3.3.070), and summary estimates (relative risk (RR), 95% CI) were calculated using a random effects model. Heterogeneity and consistency were evaluated through Cochran's Q and the I2 statistics, respectively, and sensitivity analyses were conducted.Primary and secondary outcome measuresAll-cause and cardiovascular mortality.ResultsOverall, 27 cohort studies were selected, comprising >70 000 elderly individuals, and followed up from 3.4 to 35 years. In the pooled analysis, long and short sleep duration were associated with increased all-cause mortality (RR 1.33; 95% CI 1.24 to 1.43 and RR 1.07; 95% CI 1.03 to 1.11, respectively), compared with the reference category. For cardiovascular mortality, the pooled relative risks were 1.43 (95% CI 1.15 to 1.78) for long sleep, and 1.18 (95% CI 0.76 to 1.84) for short sleep. Daytime napping ≥30 min was associated with risk of all-cause mortality (RR 1.27; 95% CI 1.08 to 1.49), compared with no daytime sleep, but longer sleep duration (≥2.0 h) was not (RR 1.34; 95% CI 1.95 to 1.90).ConclusionsAmong elderly individuals, long and short sleep duration are associated with increased risk for all-cause mortality. Long sleep duration is associated with cardiovascular mortality.

Sleep Duration and Sleep Patterns in Chinese University Students: A Comprehensive Meta-Analysis

“…Epidemiological studies usually defined self-reported short and long sleep duration as less than 6 or 7 hours per day and more than 8 or 9 hours per day, respectively. 26,[29][30][31] Some researchers suggested 7 to 8 hours per day as appropriate for the university students, whereas fewer than 7 hours is defined as short sleep and more than 8 hours is regarded as long sleep. 32,33 The National Sleep Foundation has recommended 7 to 9 hours per day as the appropriate sleep duration for young adults.…”

Sleep Duration, Mortality, and Heredity—A Prospective Twin Study

“…Several systematic reviews on sleep duration and mortality have found that the optimal sleep duration is 7 hours, with a significant increase of overall mortality for individuals with short (≤6 hours) or long (≥8 hours) sleep. [1][2][3] In a critical review, Kurina et al 4 argue that results from the literature are not totally consistent. The analysis of Kurina et al included 42 studies and only 14 of these showed a U-shaped relationship, while 23 studies (43%) showed no association at all, and the remainder showed associations for either short or long sleep.…”

Sleep duration and the risk of metabolic syndrome – a cross-sectional study

“…It has been stated in recent years that besides the traditional elements of lifestyle such as diet and physical activity, an additional factor, namely sleep, is involved in metabolic processes, hormonal functions, and energy homeostasis [1]. Tests have shown that sleep duration is associated with adverse health outcomes, such as obesity [2,3], type 2 diabetes [3][4][5], cardiovascular disease [3,6], and allcause mortality [7,8]. Inadequate sleep duration may also be a risk factor of metabolic syndrome (MetS) [9][10][11].…”