Is improving sleep and circadian problems in adolescence a pathway to improved health? A mediation analysis

Abstract

Objective: The present study tested whether improvements in sleep and circadian problems mediate the effect of a novel transdiagnostic sleep and circadian intervention (TranS-C) on improvements in 5 health domains (emotional, cognitive, behavioral, social, and physical) in community-residing, evening chronotype adolescents who were at risk for problems in these 5 health domains.

Method: Participants were 176 adolescents (age mean [SD] = 14.77 [1.84] years; 58% female) who were randomized to receive 6 sessions of TranS-C or psychoeducation. Putative mediators tested were eveningness, weekday-weekend discrepancy in total sleep time and waketime, daytime sleepiness, Pittsburgh Sleep Quality Index score, and parent-reported sleep-wake problems. Risk in 5 health domains was measured using adolescent self-reported questionnaires, parent-reported Child Behavior Checklist, and ecological momentary assessment (EMA) of problems in the 5 health domains.

Results: Reduced eveningness mediated the effects of TranS-C on reducing both self-reported and parent-reported risk in the 5 health domains. Reduction in daytime sleepiness mediated the effects of TranS-C on parent-reported risk in the 5 health domains. Reduction in parent-reported sleep-wake problems mediated the effects of TranS-C on self-reported, parent-reported, and EMA-assessed risk in the 5 health domains. Results did not support the other hypothesized mediators.

Conclusions: TranS-C exerts effects on reducing risk in multiple mental and physical health domains through reducing sleep and circadian problems in evening chronotype adolescents. Further research of TranS-C in other samples to assess its benefits for sleep and circadian problems as well as mental and physical health is warranted. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Trial registration: ClinicalTrials.gov NCT01828320.

Figure 1.

CONSORT Diagram Illustrating the Flow of Participants Through the Study *Out of 154 who were ineligible, 87 did not meet criteria for eveningness chronotype, 6 had eveningness chronotype but no risk, and 61 did not meet criteria for inclusion due to medical reasons, substance use, suicidality, trauma, or other.

Figure 2.

Conceptual Path Diagram for the Mediation Models Note. This figure shows how the mediation model is specified. The mediational or indirect effects of interest (bolded) is the product of these two bolded paths: a_m2xb_y2m2. Health Risk (indicated as circles) represents a latent variable comprised of composite scores in emotional, cognitive, behavioral, social, and physical (not shown here) domains measured by self-report (Aim 1), parent-report (Aim 2), or EMA (Aim 3). Sex and age (not shown) are added as covariates in this model. X indicates treatment comparisons TranS-C vs. PE. M indicates Sleep/Circadian mediator at baseline (M₁) and posttreatment (M₂). Y indicates Health Risk outcomes at baseline (Y₁) and posttreatment (Y₂). The path diagram includes correlation at baseline between mediator and dependent variable σ_m1y1, stability of mediator (s_m2m1) and stability of dependent variable (s_y2y1), Y₂ cross-lag (b_y2m1), M₂ cross-lag (b_m2y1), effect of X on M₂ (a_m2x), effect of X on Y₂ (c’_y2x), and effect of M₂ on Y₂ (b_y2m2). The effect of X on the mediator measured at posttreatment (M₂) adjusted for baseline mediator (M₁) is expressed as M₂ = intercept + a_m2xX + s_m2m1M₁ + b_m2y2Y₁ + e_M2. The effect of X on the outcome variable measured at posttreatment (Y₂) adjusted for the other variables is expressed as: Y₂ = intercept + c’_y2xX + s_y2y1Y1 + b_y2m1M₁ + b_y2m2M₂ + e_Y2. The mediated effect of X on Y₂ through M₂ in this model is assessed by the product of a_m2x and b_y2m2 (i.e., a_m2xb_y2m2). This figure and Table 5 are connected such that all paths that are relevant to the test of mediation are represented in Table 5 under the heading of each column (e.g., indirect effect: a_m2xb_y2m2).

Figure 3.

CMEP Mediates the Effects of TranS-C on Youth Self-Reported Health Risk. Notes. The indirect paths tested in this model are shown in bold. The indirect effects from TranS-C to Youth Self-Reported Health Risk at posttreatment via CMEP was estimated at −0.10, 95% bootstrap CI: (−0.22, −0.01) as shown in Table 5. CMEP = Children’s Morningness–Eveningness Preferences Scale. Standardized coefficients (STDY standardization) and standard errors are shown on the corresponding paths. Significant coefficients are in bold. Residuals of each indicator variable (e.g., Emotional, Cognitive) for Self-Reported Health Risk are not shown. Sex and age (not shown) are added as covariates in this model.