The longitudinal structure of sleep disturbance: Time-varying and time-invariant components and associations with psychological distress.

Sleep disturbance has increasingly been implicated in the etiology and maintenance of psychological distress. However, the time-invariant and time-varying components of sleep disturbance and their association with psychological distress are not yet understood. The present study first examined the extent to which latent sleep disturbance as indexed by sleep efficiency, perceived sleep quality, and daily disturbances is characterized by time-invariant (trait) and time-varying (state) components over a 5-month period in community adults (N = 862). The results showed that latent sleep disturbance consists of significant time-invariant and time-varying components, although the time-invariant component accounted for most of the variance (82.7%). Application of a random intercept cross-lagged panel model that allows the separation of stable between-person differences (trait-level) from dynamic within-person processes (state-level) indicated that between-person components of latent sleep disturbance and latent psychological distress were moderately positively correlated (r = .56). Although both latent variables were stable over the 5-month period within individuals, within-person deviations did not predict one another prospectively on a month-to-month basis. However, significant concurrent covariation was observed between latent sleep disturbance and latent psychological distress within individuals, with the strength of this association increasing modestly over time. These findings have implications for conceptualizing the structure of sleep disturbance as it relates to the development and maintenance of psychological distress.