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Total daily sleep duration and the risk of dementia: a prospective population-based study

Authors

  • J. Benito-León,

    1. Department of Neurology, University Hospital ‘12 de Octubre’, Madrid, Spain
    2. Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)
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  • F. Bermejo-Pareja,

    1. Department of Neurology, University Hospital ‘12 de Octubre’, Madrid, Spain
    2. Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED)
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  • S. Vega,

    1. ‘El Espinar’ Health Center, El Espinar, Segovia, Spain
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  • E. D. Louis

    1. Department of Neurology, The G.H. Sergievsky Center, College of Physicians and Surgeons, Columbia University
    2. Department of Neurology, College of Physicians and Surgeons, Columbia University
    3. Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University
    4. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY, USA
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Dr Julián Benito-León, Avda. de la Constitución 73, portal 3, 7º Izquierda, E-28821 Coslada, Madrid, Spain (tel.: 3491 6695467; fax: 3491 3908600; e-mail: jbenitol@meditex.es).

Abstract

Background and purpose:  We determined in a population-based study whether sleep duration was associated with an increased risk of incident dementia.

Methods:  In a population-based study in central Spain, participants were evaluated at baseline and 3 years later. Baseline demographic variables were recorded and participants indicated their daily sleep duration as the sum of night-time sleep and daytime napping. The average daily total sleep duration was grouped into five categories: ≤5 (short sleepers), 6, 7 (reference), 8, and ≥9 h (long sleepers). We identified all cases with incident dementia, diagnosed using DSM-IV criteria.

Results:  Three thousand two hundred eighty six participants with baseline information about sleep duration had a median duration of follow-up of 3.2 years. There were 140 incident cases of dementia. The relative risks (RR) for short sleepers and for long sleepers were 2.36 (95% CI = 1.07–5.21, P = 0.03) and 2.40 (95% CI = 1.20–4.81, P = 0.01), respectively. After adjustment for potential confounders, the RR was only marginally increased for short sleepers (1.87, 95% CI = 0.85–4.15, P = 0.12) but remained increased for long sleepers (2.18; 95% CI = 1.09–4.37, P = 0.03).

Conclusions:  Prolonged sleep duration (night-time sleep and daytime napping) may be associated with an increased risk of dementia.

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