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Medline ® Abstract for Reference 13

of 'Sleep-wake disturbances and sleep disorders in patients with dementia'

Short or long sleep duration is associated with memory impairment in older Chinese: the Guangzhou Biobank Cohort Study.
Xu L, Jiang CQ, Lam TH, Liu B, Jin YL, Zhu T, Zhang WS, Cheng KK, Thomas GN
Sleep. 2011;34(5):575. Epub 2011 May 1.
STUDY OBJECTIVES: To examine the association between sleep-related factors and memory impairment.
DESIGN: Cross-sectional study
SETTING: Community-based study in Guangzhou, China.
PARTICIPANTS: 28,670 older Chinese (20,776 women and 7,894 men) aged 50 to 85 years.
MEASUREMENTS AND RESULTS: Demographic and socioeconomic data, sleep-related factors, and cognitive function were collected by face-to-face interview. Potential confounders, such as employment and occupational status, smoking, alcohol and tea use, physical activity, self-rated health, anthropometry, blood pressure, and fasting plasma glucose and lipids were measured. After adjusting for multiple potential confounders, an inverted U-shaped association between sleep duration and delayed word recall test (DWRT) score, a validated measure of memory impairment,was found, with 7 to 8 h of habitual sleep duration showing the highest score (P-values for trend from 3 to 7 h and from 7 to≥10 h were all≤0.001). Compared to sleep duration of 7 h, the adjusted odds ratio for memory impairment from the sleep duration of 3 to 4 or≥10 h was 1.29 (95% confidence interval 1.07-1.56) and 1.52 (1.25-1.86), respectively. Subjects with daily napping, morning tiredness, or insomnia had significantly lower DWRT scores than those without (P ranged from<0.001 to 0.01).
CONCLUSIONS: Short or long sleep duration was an important sleep-related factor independently associated with memory impairment and may be a useful marker for increased risk of cognitive impairment in older people.
Department of Community Medicine, School of Public Health, University of Hong Kong, Hong Kong.