The association between interleukin-6, sleep, and demographic characteristics

We examined the relationship between the pro-inflammatory cytokine IL-6 and sleep architecture in 10 healthy men and women. Blood was drawn in the early morning for assessment of IL-6 followed by nocturnal sleep monitoring with polysominoamphy. Sleep records were scored for sleep stages using standard criteria. Morning IL-6 levels were positively correlated with REM latency after sleep onset [p =31, p =.01], percent (%) stage I sleep (p =.23 p =.053] % wake after sleep onset (WASO) [p =.29, p <.05]. IL-6 levels were negatively correlated with sleep efficiency [p = -36 p < 01] and slow wave sleep (SWS) [p = -.26. p <.05] After controlling for demographic variables including race. gender, age. and BMI multiple hierarchical regression analyses revealed that morning IL-6 levels accounted for a significant portion of the variance of REM latency (p <.01 sleep efficiency (p <.01), and % WASO (p =.01). IL-6 was no Ionger associated with % stage I sleep. SWS, and total sleep time after controlling for the demographic characteristics. These findings suggest that the inflammatory marker IL-6 is associated with sleep quality and that certain individual characteristics such as race, gender, and age modify that relationship. Higher IL-6 levels were associated with lower quality of sleep among healthy asymptomatic men and women. (C) 2004 Elsevier Inc. All rights reserved.