Objective: To examine the relationships between sleep and inflammatory markers because these may be important in the development of cardiovascular disease.
Methods and results: The relationship between self-reported sleep duration and interleukin-6 (IL-6) (n = 4642) and high-sensitivity C-reactive protein (hs-CRP) (n = 4677) was examined in individuals from the Whitehall II study. Following multiple adjustments, there were no overall linear or nonlinear trends between sleep duration and IL-6. However, in women but not men (interaction P < 0.05), levels of IL-6 tended to be lower in individuals who slept 8 hours (11% [95% confidence interval 4 to 17]) as compared to 7 hours. With hs-CRP, in the adjusted model, there was no association between hs-CRP and sleep duration in men. However, there was a significant nonlinear association in women, the level of hs-CRP being significantly higher in women short sleepers (5 hours or less) after multiple adjustments (P = 0.04) (interaction P < 0.05).
Conclusions: No significant variation in inflammatory markers with sleep duration was observed in men. By contrast, both IL-6 and hs-CRP levels varied with sleep duration in women. The observed pattern of variation was different according to the inflammatory marker observed. Further longitudinal studies are required to fully investigate possible temporal relationships between short sleep and markers of inflammation.