Figure 2.

Latent change score model for insomnia severity index (ISI) predicted by sleep–stress reactivity. Notes. Δ ISI 1 represents the latent change from baseline (T1) to 6 months later (T2). Δ ISI 2 represents the latent change from T2 to 11 months later (T3). This is a simplified representation of a univariate dual latent change score model. ISI denotes insomnia severity index. The error variances and regression coefficient for control variables (for age and night-shift status) were estimated but not included in the figure.