Insomnia symptoms are associated with elevated C-reactive protein in young adults.

OBJECTIVE: Insomnia is associated with elevated inflammation; however, studies have not investigated if this relationship is confounded with depression and neuroticism, which are associated with insomnia and inflammation. The current study examined the association of insomnia symptoms with C-reactive protein (CRP) and with interleukin-6 (IL-6), independently and after controlling for depressive symptoms and neuroticism.

DESIGN: Fifty-two young adults (mean age = 25.2 ± 3.9 years, 52% female) completed a baseline survey to assess psychological characteristics, followed by a plasma blood draw.

MAIN OUTCOME MEASURES: Plasma CRP and IL-6.

RESULTS: When examined alone, insomnia symptoms were significantly associated with elevated CRP (β = 0.52; R2  = 0.27), as was neuroticism (β = 0.41, R2  = 0.17), but not depressive symptoms (β = 0.21, R2  = 0.05). The association between insomnia symptoms and CRP remained significant when depressive symptoms and neuroticism were entered into the model simultaneously; this model did not explain more variance than the model with insomnia symptoms alone. No variables were associated with IL-6.

CONCLUSIONS: Results suggest that insomnia symptoms are independently associated with elevated CRP in young adults, even after controlling for presumed overlapping psychological constructs. Findings highlight the potential importance of treating insomnia to reduce systemic inflammation.