Normalized cumulative number of CES-D defined depression (i.e., CES-D ≥ 16) as estimated in 100 participants per group in four exposure groups: HIV+ with sleep disturbance; HIV+ without sleep disturbance; HIV- with sleep disturbance; and HIV- without sleep disturbance. The rate of slope is the linearly estimated annual incidence of depression per 100 participants: HIV+ with sleep disturbance, 31·8 per year (95% CI: 31·6–32·0); HIV+ without sleep disturbance, 18.2 without sleep disturbance (95% CI: 18·1–18·4); HIV- with sleep disturbance, 23·1 (95% CI: 22·8–23·3); and HIV- without sleep disturbance, 15.4 (95% 15·3–15·5). Each of these predicted average incidence estimates are significantly different from each other (all P's < 0·01).