Figure 2

Effect of endotoxin on cytokines ((a) IL-6; (b) TNF-α) over time in females according to sleep disturbance. Cytokines were measured at baseline (T0) and then approximately every hour after injection for the next 6 h (T1–T6). T2 was assessed at 1 h and 40 min after injection; T3 was assessed at 3 h and 30 min after injection; and T4–T6 were assessed hourly after T3. Error bars indicate 95% confidence intervals. *Marginal means adjusted for age, race, BMI and baseline depressive symptoms. BMI, body mass index; IL, interleukin; TNF, tumor necrosis factor.