Figure 2.

Associations between sleep efficiency and evening (a) and morning (b) levels of stimulated monocytic expression of TNF in RA patients and controls, as illustrated by estimated regression lines by group, controlling for depressive symptoms and physical health functioning. Curvilinear brackets indicate residual standard error. For stimulated production of TNF, results are presented as % of total number of monocytes expressing TNF, respectively, natural log-transformed.