Disentangling the effects of depression on trajectories of sleep problems from adolescence through young adulthood

Little is known about the differential influences of between- and within-person effects of depression as well as its long-term impacts on sleep problems in adolescents. This study aims to disentangle these differences by estimating three effects of depression (i.e., long-term, immediate, and fluctuating).

The sample included 1345 males and 1283 females in Taiwan. In multilevel models, the between- (i.e., long-term and immediate) and within-person (i.e., fluctuating) effects were estimated by using the average and time-varying scores of depression, respectively. The interactions between long-term and the other effects were also tested to determine the moderating effects of long-term influences.

Significant immediate and long-term effects of depression were found for both sexes, indicating that adolescents with higher levels of depression were at increased risks for future sleep problems. For females only, the long-term effects further exacerbated the negative influences of immediate effects of depression on sleep problems. Moreover, the fluctuating effects were found to change over time in females and the influences were more pronounced in young adulthood.

The self-reported measures of both depression and sleep problems may produce common method variance and bias the results. Our measurements were adapted from various existing scales to increase their applicability; therefore, the internal consistency was not high.

Our findings provide insight regarding who is at risk for sleep problems and when this risk would occur based on the effects of depression. They also highlight the importance of both immediate and long-term effects of depression on development of sleep problems.