Article

Change in sleep duration and cognitive function: findings from the Whitehall II Study.

University College London, Department of Epidemiology and Public Health, London, UK.
Sleep (Impact Factor: 5.1). 05/2011; 34(5):565-73.
Source: PubMed

ABSTRACT Evidence from cross-sectional studies shows that sleep is associated with cognitive function. This study examines change in sleep duration as a determinant of cognitive function.
Prospective cohort.
The Whitehall II study.
1459 women and 3972 men aged 45-69 at baseline.
None.
Sleep duration (≤ 5, 6, 7, 8, ≥ 9 h on an average week night) was assessed once between 1997-1999, baseline for the present study, and once between 2002-2004, average follow-up 5.4 years. Cognitive function was measured (2002-2004) using 6 tests: verbal memory, inductive reasoning (Alice Heim 4-I), verbal meaning (Mill Hill), phonemic and semantic fluency, and the Mini Mental State Examination (MMSE). In analyses adjusted for age, sex, and education, and corrected for multiple testing, adverse changes in sleep between baseline and follow-up (decrease from 6, 7, or 8 h, increase from 7 or 8 h) were associated with lower scores on most cognitive function tests. Exceptions were memory, and, for a decrease from 6-8 h only, phonemic fluency. Further adjustment for occupational position attenuated the associations slightly. However, firm evidence remained for an association between an increase from 7 or 8 h sleep and lower cognitive function for all tests, except memory, and between a decrease from 6-8 h sleep and poorer reasoning, vocabulary, and the MMSE. The magnitude of these effects was equivalent to a 4-7 year increase in age.
These results suggest that adverse changes in sleep duration are associated with poorer cognitive function in the middle-aged.

0 0
 · 
0 Bookmarks
 · 
65 Views
  • [show abstract] [hide abstract]
    ABSTRACT: It is not clear whether cognitive decline progresses more quickly in long sleepers than in short sleepers or than in participants with usual sleep duration. We assessed cognitive decline as a function of self-reported sleep duration in a prospective population-based cohort (NEDICES). Participants were evaluated at baseline and 3 years later. Baseline demographic variables were recorded and participants indicated their daily sleep usual duration as the sum of nighttime sleep and daytime napping. The average daily total usual sleep duration was grouped into three categories: ≤5 h (short sleepers), 6-8 h (reference category), and ≥9 h (long sleepers). At baseline and at follow-up, a 37-item version of the Mini-Mental State Examination (37-MMSE) was administered. The final sample, 2715 participants (72.9 ± 6.1 years), comprised 298 (11%) short sleepers, 1086 (40%) long sleepers, and 1331 (49%) in the reference group (6-8 h). During the three year follow-up period, the 37-MMSE declined by 0.5 ± 4.0 points in short sleepers, 0.6 ± 4.3 points in long sleepers, and 0.2 ± 3.8 points in the reference group (p = 0.08). The difference between short sleepers and the reference group was not significant (p = 0.142); however, the difference between long sleepers and the reference group was significant (p = 0.040). In analyses adjusted for baseline age and other potential confounders, this difference remained robust. In this study, cognitive test scores among long sleepers declined more rapidly than observed in a reference group. Additional studies are needed to confirm these results.
    Journal of psychiatric research 09/2013; · 3.72 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: This study assessed the association of sleep quality with academic performance among university students in Ethiopia. This cross-sectional study of 2,173 college students (471 female and 1,672 male) was conducted in two universities in Ethiopia. Students were selected into the study using a multistage sampling procedure, and data were collected through a self-administered questionnaire. Sleep quality was assessed using Pittsburgh Sleep Quality Index, and academic performance was based on self-reported cumulative grade point average. The Student's "t" test, analysis of variance, and multiple linear regression were used to evaluate associations. We found that students with better sleep quality score achieved better on their academic performance (P value = 0.001), while sleep duration was not associated with academic performance in the final model. Our study underscores the importance of sleep quality on better academic performance. Future studies need to identify the possible factors which influence sleep quality other than the academic environment repeatedly reported by other literature. It is imperative to design and implement appropriate interventions to improve sleep quality in light of the current body of evidence to enhance academic success in the study setting.
    Sleep And Breathing 08/2013; · 2.26 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Objectives Sleep patterns have been linked to various health outcomes, but sleep patterns in the British population have not been extensively reported. We aimed to describe the sleep characteristics reported by the European Prospective Investigation of Cancer (EPIC)-Norfolk participants, with a particular emphasis on the comparison of measures of sleep quantity. Methods From 2006 to 2007, a total of 8480 participants aged 45 to 90 years reported sleep timing, nighttime sleep duration, and sleep difficulties. Time in bed (TIB) was calculated from the difference between rise time and bedtime, and sleep proportion was defined as the ratio of sleep duration and TIB. Results On average, the reported TIB was more than 1.5 hour longer than sleep durations. Compared to men, women spent 15 minutes longer in bed, but they slept for 11 minutes less and reported more sleep difficulties. In multivariate analysis sleep duration and TIB varied with socioeconomic factors, but sleep proportion was consistently lower among women, nonworkers, older individuals; those who were widowed, separated, or divorced; those who reported sleep difficulties and more frequently used sleep medication; and those who had lower education, poorer general health, or major depressive disorder. Conclusions Self-reported sleep duration and TIB have different meanings and implications for health. Sleep proportion may be a useful indicator of sleep patterns in the general population.
    Sleep Medicine 01/2014; · 3.49 Impact Factor

Full-text (2 Sources)

View
12 Downloads
Available from
Aug 13, 2013