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dc.contributor.authorLeng, Yueen
dc.contributor.authorAhmadi-Abhari, Saraen
dc.contributor.authorWainwright, Nick WJen
dc.contributor.authorCappuccio, Francesco Pen
dc.contributor.authorSurtees, Paul Gen
dc.contributor.authorLuben, Roberten
dc.contributor.authorBrayne, Carolen
dc.contributor.authorKhaw, Kay-Teeen
dc.date.accessioned2014-11-12T11:12:00Z
dc.date.available2014-11-12T11:12:00Z
dc.date.issued2014-11-11en
dc.identifier.citationBMJ Open 2014, 4:e006071. doi:10.1136/bmjopen-2014-006071en
dc.identifier.issn2044-6055
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/246347
dc.description.abstract$\textbf{Objectives:}$ To explore whether daytime napping and sleep duration are linked to serum C reactive protein (CRP), a pro-inflammatory marker, in an older aged British population. $\textbf{Design:}$ Cross-sectional study. $\textbf{Setting:}$ European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk study. $\textbf{Participants:}$ A total of 5018 men and women aged 48–92 years reported their sleep habits and had serum CRP levels measured. $\textbf{Outcome and measures:}$ CRP was measured (mg/L) during 2006–2011 in fresh blood samples using high-sensitivity methods. Participants reported napping habits during 2002–2004, and reported sleep quantity during 2006–2007. Multivariable linear regression models were used to examine the association between napping and log-transformed CRP, and geometric mean CRP levels were calculated. $\textbf{Results:}$ After adjustment for age and sex, those who reported napping had 10% higher CRP levels compared with those not napping. The association was attenuated but remained borderline significant (β=0.05 (95% CI 0.00 to 0.10)) after further adjustment for social class, education, marital status, body mass index, physical activity, smoking, alcohol intake, self-reported health, pre-existing diseases, systolic blood pressure, hypnotic drug use, depression and in women-only hormone replacement therapy use. The geometric means (95% CI) of CRP levels were 2.38 (2.29 to 2.47) mg/L and 2.26 (2.21 to 2.32) mg/L for those who reported napping and no napping, respectively. A U-shaped association was observed between time spent in bed at night and CRP levels, and nighttime sleep duration was not associated with serum CRP levels. The association between napping and CRP was stronger for older participants, and among extremes of time spent in bed at night. $\textbf{Conclusions:}$ Daytime napping was associated with increased CRP levels in an older aged British population. Further studies are needed to determine whether daytime napping is a cause for systemic inflammation, or if it is a symptom or consequence of underlying health problems.
dc.description.sponsorshipThe design and conduct of the EPIC-Norfolk study and collection and management of the data was supported by programme grants from the Medical Research Council UK (G9502233, G0300128) and Cancer Research UK (C865/A2883). YL is supported by the Cambridge Overseas Trust. FPC leads the Sleep Health & Society Programme at the University of Warwick supported, in part, by the University of Warwick RDF and IAS. It has received funding by the NHS National Workforce Projects and the Economic & Social Research Council (ES/K002910/1).
dc.languageEnglishen
dc.language.isoenen
dc.publisherBMJ Group
dc.rightsAttribution 2.0 UK: England & Wales
dc.rights.urihttp://creativecommons.org/licenses/by/2.0/uk/
dc.subjectSleepen
dc.subjectNappingen
dc.subjectC-reactive proteinen
dc.subjectInflammationen
dc.subjectPopulationen
dc.titleDaytime napping, sleep duration and serum C-reactive protein: a population-based cohort studyen
dc.typeArticle
dc.description.versionThis is the final version. It was first published by BMJ Group at http://bmjopen.bmj.com/content/4/11/e006071.full.en
prism.numbere006071en
prism.publicationDate2014en
prism.publicationNameBMJ Openen
prism.volume4en
dc.rioxxterms.funderMRC
dc.rioxxterms.funderMRC
dc.rioxxterms.funderCRUK
dc.rioxxterms.funderCRUK
dc.rioxxterms.funderESRC
dc.rioxxterms.projectidG9502233
dc.rioxxterms.projectidG0401527
dc.rioxxterms.projectidC864/A8257
dc.rioxxterms.projectidC864/A2883
dc.rioxxterms.projectidES/K002910/1
rioxxterms.versionofrecord10.1136/bmjopen-2014-006071en
rioxxterms.versionVoR
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2014-11-11en
dc.contributor.orcidLuben, Robert [0000-0002-5088-6343]
dc.contributor.orcidBrayne, Carol [0000-0001-5307-663X]
dc.contributor.orcidKhaw, Kay-Tee [0000-0002-8802-2903]
dc.identifier.eissn2044-6055
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idMRC (G0401527)
pubs.funder-project-idMRC (G1000143)
pubs.funder-project-idMRC (G0500300)
pubs.funder-project-idMRC (G0800603)
pubs.funder-project-idCancer Research UK (A8257)
pubs.funder-project-idCancer Research UK (A2883)


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Attribution 2.0 UK: England & Wales
Except where otherwise noted, this item's licence is described as Attribution 2.0 UK: England & Wales