Sleep duration and biomarkers of inflammation.
BACKGROUND
Extremes of sleep duration have been associated with adverse health outcomes. The mechanism is unclear but may be related to increased inflammation. We sought to assess the association between sleep duration and inflammatory biomarkers.


METHODS
A total of 614 individuals from the Cleveland Family Study completed questionnaires about sleep habits and underwent polysomnography. A morning fasting blood sample was assayed for 5 inflammatory cytokines.


RESULTS
In this cohort, mean (SD) habitual sleep duration based on self-report was 7.6 (1.6) h and mean sleep duration by polysomnography (PSG) on the night prior to blood sampling was 6.2 (1.3) h. After adjusting for obesity and apnea severity, each additional hour of habitual sleep duration was associated with an 8% increase in C-reactive protein (CRP) levels (P=0.004) and 7% increase in interleukin-6 (IL-6) levels (P=0.0003). These associations were independent of self-reported sleepiness. In contrast, PSG sleep duration was inversely associated with tumor necrosis factor alpha (TNFa) levels. For each hour reduction in sleep, TNFalpha levels increased by 8% on average (P=0.02). Sleep duration was not associated with IL-1 or IL-10.


CONCLUSIONS
Increases in habitual sleep durations are associated with elevations in CRP and IL-6 while reduced PSG sleep duration is associated with elevated TNFa levels. Activation of pro-inflammatory pathways may represent a mechanism by which extreme sleep habits affect health.
Patel
Sanjay R
SR
Division of Pulmonary, Critical Care and Sleep Medicine, University Hospital Case Medical Center and Case Western Reserve University, Cleveland, OH, USA. srp20@case.edu
Zhu
Xiaobei
X
Storfer-Isser
Amy
A
Mehra
Reena
R
Jenny
Nancy S
NS
Tracy
Russell
R
Redline
Susan
S
D000328:Adult; D002097:C-Reactive Protein / Q000378:metabolism; D015331:Cohort Studies; D006970:Disorders of Excessive Somnolence / Q000235:genetics / Q000276:immunology*; D005260:Female; D006306:Health Surveys; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D007375:Interleukin-1 / Q000097:blood; D016753:Interleukin-10 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics / Q000276:immunology; D010641:Phenotype; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000235:genetics / Q000276:immunology*; D012892:Sleep Deprivation / Q000235:genetics / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D018836:Inflammation Mediators; D007375:Interleukin-1; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D002097:C-Reactive Protein